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Royal Air Force Typhoon jets have arrived at an airbase in London for a large-scale Olympic security exercise.

The aircraft will be based at RAF Northolt, taking part in eight days of training over London and the home counties until 10 May, as part of operation Exercise Olympic Guardian.

It is the first time fighter jets have been stationed at the west London site since WWII.

But anti-military campaigners warn the jets will create a "climate of fear".

The Typhoon jets, which can travel at up to 1,370 miles per hour, will put pilots through their paces, testing security in the skies ahead of their vital role during the 2012 Olympic Games, which start in July.

Military chiefs have alerted residents in south-east England about the operation, warning that they will notice an increase in often loud air activity, especially on 4 and 5 May.

Defence Secretary Phillip Hammond said: "Whilst there is no specific threat to the Games, we have to be ready to assist in delivering a safe and secure Olympics for all to enjoy."

He said the Typhoon operation at RAF Northolt underlined the "commitment of the Ministry of Defence and our armed forces to keeping the public safe at a time when the world will be watching us".

But the Stop the War Coalition has criticised the move as "unacceptable", arguing that heavy military activity in the capital will cause unnecessary fear.

Lindsey German of the campaign group said ordinary people should not be forced to put up with the measures.

"Far from safeguarding Londoners as they go about their daily lives, they will bring a real fear of explosions and the prospect of these places becoming a target for terrorist attack."

"We are told by the Government that the war in Afghanistan is being fought so that we don't have to fight on the streets of London", she said.

"These manoeuvres give the lie to that, and show that the war has made Britain a more dangerous place."

Air Vice-Marshal Stuart Atha, air component commander for Olympics air security, said the training was "essential" and in line with "preparations for most Olympics" in recent years.

"What we have is just prudent precautionary measures in place in the unlikely event that a threat from the air does manifest itself."

He denied fighter aircraft would be patrolling the skies as a matter of course throughout the summer, adding the operation "would not set a precedent for any sort of enduring military commitment" in the area.

"This is a once in a generation event and I think the UK public would expect us to be prepared for this", he said.

However, he added the MoD would try to keep the amount of flying to a minimum, balancing the need to reduce disturbance with the key aim of ensuring forces are "ready for their important role delivering air security for the Olympics".

"We hope that people will understand the need for this very important training, and we thank them for their continued strong support", he said.

Exercise Olympic Guardian is taking place on land, sea and air in the London and Weymouth areas between 2 May and 10 May.

The security operations will also include:

It was also recently revealed that surface-to-air missiles could be deployed at six sites in London during the games.

Last month, a sonic boom from two Typhoon aircraft that were responding to an emergency signal was reported to have been heard in Bath, Coventry and Oxford.