Two Americans have been left injured after a man with a knife attacked tourists at the Acropolis in Athens on Tuesday morning.

The incident happened shortly after 8am when a passer-by alerted emergency services to a man armed with a knife who was threatening tourists gathered near the ticket office.

Police were immediately dispatched to the scene, where they found the suspect had already attacked two American tourists, leaving them with minor injuries to their hands.

An ambulance was called to treat the victims at the scene.

The suspect, who according to initial reports is believed to have mental health issues, was restrained and arrested by officers from the Athens Police Department.

The Acropolis of Athens (file pic)