UK police said Friday officers had carried out a controlled explosion after "a suspicious package" was found outside the United States embassy in London.

The capital's Metropolitan Police force conducted the explosion after setting up cordons near the high-security site in Nine Elms, just south of the River Thames.

"We can confirm that the 'loud bang' reported in the area a short time ago was a controlled explosion carried out by officers," the force said in a post on X.

"Enquiries are still ongoing and cordons will remain in place for the time being."

The US embassy said in a post on the same platform that local authorities were investigating "a suspicious package" outside the building.

It added that police had closed a nearby road "out of an abundance of caution."

In another sign that UK authorities were on high alert, Gatwick Airport said a "large part" of its south terminal "has been evacuated as a precaution while we continue to investigate a security incident.'

"Passengers will not be able to enter the South Terminal while this is ongoing. Safety and security of our passengers and staff remains our top priority," it said on X.

"We are working hard to resolve the issue as quickly as possible," the statement added, without providing further details.