Hundreds of train drivers in central England will go on strike for three days during the Olympic Games, their trade union said on Thursday, a move that could disrupt journeys to London from elsewhere in Britain during the historic event.

It was the second Olympics strike threat in as many days after border officials voted on Wednesday to walk out, raising the spectre of huge passport queues at Heathrow airport.

The Aslef rail union said around 450 of its members will walk out between Aug. 6-8 in a dispute over pension contributions. The Games run from 27 July to 12 August. 

The strike - by East Midlands Trains drivers - could disrupt the journeys of thousands of passengers travelling from English cities like Sheffield, Nottingham and Derby to London for the Games.

East Midlands Trains also runs services to Leicester, about 25 miles (40 km) from the City of Coventry Stadium, which hosts the women's bronze medal soccer match the day after the strike is due to end.

East Midlands Trains called on the union to hold more talks to avoid the strike. If it did go ahead, it said it would do all it could to prevent disruption.

Transport will be one of the biggest tests for the Games' organisers. There are no car parking spaces at London venues and all spectators will be expected to walk, cycle or use public transport.

Britain's rail and road network often struggles to cope with demand during busy periods and some fear the Olympics will prove too great a burden.

Extra staff have been deployed at airports to cut queues and more than 100 miles of main roads in London will have special lanes reserved for athletes and officials.

Border officials were expected to announce details of their industrial action over pay and conditions later on Thursday after a turnout of only 20 percent in their strike ballot.