Illegal migrants are feared to be on the run from the authorities after arriving undetected in a sleepy Cornish harbour.

Locals at Mylor, near Falmouth, said 18 migrants fled into the darkness after arriving aboard a yacht in the early hours of Sunday.

Two Albanian men were arrested at the scene, a Devon and Cornwall Police spokesman said.

But others were driven away in a van.

Eight other arrests were understood to have been made later in a different police force area.

An individual thought to be under 18 was also referred to social services, the Home Office said.

It comes after two small boats reached UK shores without being intercepted by Border Force last week.

A spokesman for Devon and Cornwall Police said: ‘We were called shortly before 3am on Sunday September 27 following a report of a number of individuals exiting a boat at Mylor harbour, entering a van and then leaving the area.

‘Officers attended and arrested two Albanian nationals on suspicion of immigration offences.

‘[The Home Office agency] Immigration Enforcement is leading the investigation.’

A spokesman for HM Coastguard confirmed it had assisted police response to the incident.

Home Office officials are leading an investigation into 18 migrants reported to have landed at  Mylor harbour, pictured, in Cornwall before getting into a van and disappearing into the night

A Home Office spokesman said: ‘Officers responded quickly to an isolated and rare incident at Mylor Harbour, Falmouth.

‘Ten individuals have since been arrested. Another individual understood to be under 18 was referred to social services.

‘There is an ongoing investigation, and it would be inappropriate to comment further.’

Last Monday witnesses said a small boat carrying at least seven migrants landed just off the Warren nature reserve, east of Folkestone.

The following day up to 30 people arrived on Samphire Hoe between Dover and Folkestone.

Cabinet minister Lucy Powell admitted last week that the Government ‘can’t stop everything all of the time’ as she was grilled over a week of chaos.

It came after a Border Force union warned last week that migrant boats were ‘definitely’ arriving on British shores completely undetected along the full length of the south coast.

The ISU union’s Lucy Moreton said: ‘It’s absolutely, definitely happening.

‘If no-one sees them, no-one sees them.

‘But we know that we’ve had abandoned vessels, we’ve had reports of uncontrolled landings all the way down to Falmouth.

‘Ultimately, we do not know how many are not identified, or how many are lost at sea, because we just don’t have that monitoring that we do from the beaches around the Calais area.’

Ms Moreton accused the Home Office of taking a position of: ‘If we don’t look for it, we don’t know it’s happening. We don’t know it’s happening, we don’t have to deal with it.’

The latest development came as three more migrants, including a child, tragically died in the Channel.

A 10-year-old child and two women were confirmed dead after their boat got into difficulty in the Channel.

French authorities said 105 people on board the migrant dinghy were rescued after calling for assistance.

A medical team was transported to the rescue boat by helicopter to help the survivors, but the child and two women could not be saved.

The accident happened after the dinghy had left Bleriot Plage, near Calais, on Monday morning, with ship tracking data showing rescue boats still in the area.