Reform UK has pledged to launch ‘the biggest military operation in the Channel since World War Two’ to end migrant crossings.

The plan, branded Operation Fortress, would see the Royal Navy put to work protecting Britain’s borders and towing any small boats back to France.

Reform’s home affairs spokesman Zia Yusuf will unveil the policy later on Monday, at the start of a week of announcements by the party on migration.

Watch the announcement LIVE: 

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He will be flanked by as-yet unnamed senior former members of the Armed Forces – who Reform claim have endorsed the scheme as ‘operationally feasible’, and one the rank-and-file of the military ‘will be ready and able to do’.

Mr Yusuf will say Britain is being ‘invaded’, accusing Tory and Labour governments of responding to the crisis by offering ‘a free ferry service and free hotels’.

He will say: ‘Nigel Farage will order His Majesty’s Royal Navy to ensure that not a single unauthorised vessel crossing the English Channel makes it to the shores of the United Kingdom.

‘Those who attempt it will be intercepted by our Armed Forces and returned to France.’

Mr Yusuf also told the Daily Mail the Navy will be permitted to use lethal force if intelligence agencies confirm the presence of known terrorists or smuggling gang leaders.

Operation Fortress will be unveiled by Reform UK’s home affairs spokesman Zia Yusuf

The plan would see the Royal Navy put to work protecting Britain’s borders and towing any small boats back to France. Mr Yusuf pictured last week at Ceuta after 60,000 illegal migrants came through Spain’s border 

He said: ‘Once the world realises that crossing the Channel illegally leads only to being intercepted by our Royal Marines and returned to France, the incentive structure breaks. 

‘These economic migrants will stop paying smugglers and the boats will stop coming. That is how we will stop the boats. Reform will stop the invasion.’

More than 160 migrants have died trying to cross the Channel since 2018. Reform insists that the plan is legal under international law, citing the requirement to preserve life at sea.

But it is likely to face significant challenges and opposition.

International maritime law allows states to pick up people from vessels when they are found to be in distress at sea.

But the laws do not permit those individuals to be transferred to another state unless that country has agreed to receive them.

It is unlikely the French would react positively to the Navy towing migrants back to their shores.

Reform admits the plan relies on the French complying with their obligations to stop the crossings.

The party appeared to issue a dare to the French president, stating: ‘We do not believe Emmanuel Macron would order the French navy to open fire on a boat full of civilians escorted by Royal Marines conducting a humanitarian mission.’ 

Mr Yusuf on Monday morning defended the proposals against claims the Royal Navy currently doesn’t have enough ships to return migrants back across the Channel, or that France would simply refuse to accept them.

Tom Sharpe, a former Royal Navy commander, said Reform’s policy ‘starts to unravel quite quickly’.

‘There’s a notion that the Royal Navy could steam in over the horizon and fix this problem, which is declining slightly anyway,’ he told BBC Radio 4’s Today programme.

‘The reality, when you start looking at what ships we have, which is basically none.

‘He’s talking about the largest maritime operation in the Channel since World War Two – a very evocative image, but that’s not the reality. We don’t have the ships.

‘And if you do bring your ships to bear, and you start investigating what exactly you’re going to do with them and where, it starts to unravel quite quickly.’

He added: ‘A billion pound warship that’s configured for anti-air warfare or anti-submarine warfare, which are both threats to the UK, is not best used ferrying people around. You’re better off using an actual ferry.’

Mr Yusuf said under the plans, the Navy will be permitted to use lethal force if intelligence agencies confirm the presence of known terrorists or smuggling gang leaders on small boats

But responding to those criticisms, Mr Yusuf told the same programme: ‘The vessels we are talking about using are first of all the Bay Class ships, the second one would be offshore river patrol vessels, and on those vessels you have things called RHIBs; rigid hulled inflatable boats.

‘These are very small, highly manoeuvrable Navy vessels which will have Royal Marines on board that will be used to go right up alongside these illegal migrant dinghies, take them on board and escort them back to France.’

Asked what would happen if France refused to accept migrants that had been returned by Britain’s military, Mr Yusuf said: ‘In the event they do not consent the marines will nevertheless… escort the migrants onto the beaches of France and if the French disagree what will end up happening is we will end up having something of an argument with the French.’

He questioned why UK politicians would be ‘unwilling to have an argument with the French and the Elysee Palace over the invasion of Britain’.

Pressed further on what would happen if France did not let the migrants disembark on its beaches, Mr Yusuf added: ‘That would mean the French committing a crime against humanity, that is what would be happening.

‘This is a boat full of innocent civilians who are being rescued as part of a humanitarian mission.

‘If the French chose to do as you’re suggesting… the idea that President [Emmanuel] Macron would order the gendarmerie, the coastguard or anybody else under his control to commit a crime against humanity… I do not think that is a serious hypothetical.’

He went on: ‘We’ve got extensive legal opinion on this, it is legal.’

Robert Jenrick, as immigration minister in the last Tory government before defecting to Reform, ditched plans to turn dinghies back to France in 2022.

France has previously said that such plans would break international maritime law.

At the time Mr Jenrick said: ‘There are limited circumstances in which small boats can be turned around safely in the English Channel.’

Mr Yusuf will set out plans to make the Channel ‘the world’s most surveilled maritime border’ on Monday, with a Reform government creating an Integrated Surveillance Command that gives real-time ability to track all incoming boat launches using drones, the coastguard, helicopters and satellites.

Tory shadow home secretary Chris Philp accused Reform of putting forward ‘slogans and policies written on the back of a fag packet but no credibility behind it – they can’t answer basic questions like how they would properly fund the military’.

He added: ‘They haven’t even got a defence spokesman and they can’t answer basic questions like what they would do if the French refuse to allow the illegal immigrants to be disembarked back in France.’

Mr Philp said the Conservatives ‘would deport these illegal immigrants back to their country of origin, and if that’s not possible, a safe third country like Rwanda’.

Labour’s Miatta Fahnbulleh defended the Government’s drive to cut the number of migrants entering the UK.

The Energy Secretary signalled ministers would stick with their current plan to reduce the number of small boat crossings ‘because it is working – 50 per cent down on last year’. 

The Cabinet minister told Sky News: ‘I think the crossings this July were the lowest we’ve had for six years and we need to continue that.

‘And the approach that we are taking is threefold. It’s partly about enforcement, so we’ve seen a doubling of enforcement officers to make sure that people aren’t getting on those boats to begin with, and if they are and they need to be returned, they’re returned.

‘But secondly, it is about making sure that we are getting to grips with the criminal gangs that are at the heart of this – we’ve seen an increase in arrests of about 74 per cent.

‘And then the third plank is making sure that there are safe and legal routes. We think that approach is working – 50 per cent down. Everyone wants to see an end to small boats crossing.

‘It is a nightmare for the people who are on those boats, putting their lives at risk. It is a nightmare for us trying to control our borders.’

A Labour spokesman accused Reform of ‘reheating an old announcement in their desperate bid to distract from sleaze scandals.

‘The actions we’ve taken have started to have a real impact and led to 46,000 attempted crossings stopped, and 70,000 people with no right to be here removed,’ they said.