Updated

By Avril Ormsby

LONDON (Reuters) - Britain's military launched a charm offensive on Thursday to calm residents' fears over plans to put missile batteries on their rooftops to protect this summer's Olympics from a possible 9/11-style attack.

"We want the focus to be on (Jamaican sprinter) Usain Bolt this summer and not us," said Air Vice-Marshal Stuart Atha, speaking at a cadet centre near Blackheath Common in southeast London, one of six potential sites for the anti-aircraft weapons.

An eight-day military exercise codenamed Olympic Guardian, began this week to test operations for a safe Games in July in what will be Britain's biggest peacetime security operation.

Missiles could be placed on a disused water tower in an apartment complex in Bow, next to the Olympic Park in east London, after defense chiefs decided against putting them inside the Games complex.

"We're trying to demilitarize this and let the sport do the talking," said Colonel Jon Campbell, commander of joint ground based air defense.

Some residents in the red-brick development of 700 flats in Bow have said they fear the missiles could make them a terrorist target and questioned the wisdom of shooting down an aircraft over a built-up area.

One high-profile critic at the apartments said he was even being evicted after raising concerns about the missiles in television and newspaper interviews.

"We received a phone call saying she (the landlady) was unhappy about the cameras and that we were being asked to leave. Maybe she panicked," said Brian Whelan, a 28-year old journalist.

Campbell said the military were trying to reassure residents but accepted that some people would remain concerned.

"You cannot please everyone all the time," he said.

"We've done wherever possible as much as we possibly can to allay people's fears ... we are in the front of your minds at this moment, but once this weekend has passed we very much hope that we can fade into the background," he added.

The High Velocity Missile (HVM) batteries being placed on the tower in Bow and on an apartment block in north London will be loaded with dummy shells for the exercise. The missiles have not been fired in anger since they went into service in the early 1990s.

The other four sites around the capital are on more open ground and will be equipped with the Rapier missile system, which can be used against planes, helicopters and cruise missiles.

A final decision on whether to deploy the anti-aircraft weapons during the Games, which start on July 27, will be taken by ministers after the military exercise.

Surface-to-air missiles have been rolled-out at previous Olympics, both before and after the September 11 attacks on the United States, and routinely at the World Economic Forum at Davos, the annual meeting of world political and business elites in Switzerland, Campbell noted.

Any order to shoot down an aircraft would be a last resort and made at the highest levels of government, the military chiefs insisted.

As one of the biggest supporters of the U.S. invasions of Iraq and Afghanistan, Britain has long been regarded as a prime target for terrorists.

Suicide bombers killed 52 people in co-ordinated attacks in London on the day after the city was awarded the Games in July 2005.

(Additional reporting by Georgina Cooper; Editing by Tim Castle)