Britain's Royal Air Force said Friday it was ready to use "lethal force" against aircraft which flout flying restrictions being put in place for the London Olympics.
A series of airspace restrictions around London and the wider southeast England region will come into force from midnight (2301 GMT) Friday, designed to protect the capital during the Games which begin on July 27, the RAF said.
Typhoon jets and Puma helicopters with snipers will be patrolling the restricted zone and intercepting any aircraft which should not be inside it.
"As a last resort, we will have lethal force as an option," said Air Vice-Marshal Stuart Atha, the Olympics air security commander, at a briefing at the RAF Northolt base in west London.
He said such any decision would be made at "the highest level of government" and would be the "worst-case scenario".
The restricted area includes a small inner zone covering central London and the Olympic Park in Stratford, east London, and a large zone covering part of southeast England.
Light aircraft, gliders and hot air balloons will be expected to adhere to the restrictions, which will remain in place until August 15, but commercial flights will not be affected.
Other measures to protect London from aerial threats include the deployment of missile defence systems at six sites in east London, while Royal Navy Sea King helicopters will also be based at RAF Northolt.
Aviation authorities have conducted Britain's largest ever pilot education programme to ensure the restrictions are understood, the RAF said.
Helicopter carrier HMS Ocean, the Royal Navy's largest ship, is due to arrive in Greenwich, southeast London, late Friday where it will be moored on the River Thames during the Games as a base for helicopters and military personnel.