Thousands of members of the Public and Commercial Services (PCS) union at the Home Office decided on the strike due to their anger over cuts to UK border staff, pay and other issues.

Although a date for the strike has not been set, it is of huge concern due to that fact that it could leave all of the main London 2012 transport hubs, including Heathrow, which is the Official Host Airport for Games, short of border staff in what is their busiest ever period with the Games looming.

"We believe Ministers have acted recklessly and irresponsibly in cutting so many jobs and, in the case of UK Border Agency, they have simply tried to paper over the cracks by deploying severely undertrained staff at our borders," said the PCS general secretary Mark Serwotka.

"If these issues are not resolved, they threaten to seriously undermine the Home Office's ability to provide vital public services and we cannot sit back and allow that to happen."

The PCS is one of the largest unions in the UK with around 250,000 public sector members but Immigration Minister Damian Green has slammed the move, calling it "completely unacceptable" and something the public would not tolerate with London 2012 just over a week away.

"Only about one in 10 PCS members voted for strike action," said Green.

"The union leadership has no authority to call disruptive strikes on that basis and should think again.

"The security of the UK border is of the utmost importance and we will use our trained pool of contingency staff to ensure we minimise any disruption caused by planned union action.

"Any action that disrupts the Olympics will be completely unacceptable and the public will not support it."

A Russian Olympic team official is given assistance at Heathrow Airport after arriving there earlier this week

The news could not come at a worse time for Heathrow, the third busiest airport in the world and the main point of entry for the Olympics and Paralympics, with an estimated 80 per cent of people travelling to the Games from outside the UK passing through the facility.

The biggest logistical challenge for Heathrow will come next month on August 13, the day after the Olympic Closing Ceremony, because it is set to be the busiest day in the airport's history and the number of bags expected to leave the airport will be more than 25 per cent higher than usual peak times.

Around 15 per cent of the bags are likely to consist of large sporting equipment such as canoes, pole vaults or bikes, which cannot be processed through normal baggage systems.

Businesses and airlines have long argued that Heathrow needs another runway to cope with rising demand, but the move has been consistently blocked by the Government because of environmental concerns.

The move will also provide further headache for London 2012 after Games security contractor G4S admitted they would not be able to train enough security guards in time for the Olympics.

This forced the Government to step in and deploy of 3,500 troops to make up the shortfall.

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