Heavy duty military aircrafts were spotted soaring the skies on Thursday as Ospreys flew across west London.
A Ministry of Defence spokesperson told getwestlondon: "We don’t own any Ospreys, they are likely to be US air force assets.
"It is almost certain that they were using the Thames as the helicopter transit route through London (which would be the same for civilian or military helicopters) and were simply moving from one place to another."
They added: "There was no military exercise involving any UK personnel, contrary to some reports."
Social media users took to Twitter to capture the unusual helicopters as they spotted them over Chiswick.
Office workers in the capital were also quick to spot the impressive choppers.
The aircraft can reportedly fly without having to refuel for eight hours, equal to 1,000 hours.
Each of its three 19ft-long rotors attached to each wing can, as their name suggests, rotate 90 degrees - along with its engine - after it takes off like a helicopter to transform into a fixed-wing craft and fly at high-speed.