Police in London arrested a man on Tuesday after a stabbing outside the British Museum which reportedly led to the evacuation of the popular tourist attraction.

The incident unfolded at around 10am (0900 GMT) on the street bordering the southern perimeter of the world-famous site, according to London's Metropolitan Police.

"Police have arrested a man on suspicion of grievous bodily harm following an incident," the force said.

"A man was treated for a stab wound to the arm at the scene and taken by London Ambulance Service to hospital.

"His condition is being assessed."

The Met said it was "an isolated incident" and there was no remaining risk to the public. 

"It is not being treated as terror-related," the force added, noting the immediate area may remain restricted "for much of today".

The museum, which first opened its doors in 1759, was evacuated following the stabbing, according to British news outlets and social media posts. 

The site, in the heart of the capital, is a huge draw for tourists, particularly in peak summer months such as August.