London bus workers are to stage two fresh strikes in a dispute over an Olympics bonus, including one walkout just days before the Games start.
The Unite union said its members will strike on Thursday July 5 and again on Tuesday July 24, three days ahead of the official opening of the sporting event.
The workers went on strike last Friday, causing travel chaos for tens of thousands of passengers and disrupting services across the capital.
The union is seeking a bonus of £500 for its 21,000 members at 20 bus companies, pointing out that other transport workers have been promised a premium payment for working during the Games.
Unite warned that bus services would come to a standstill on July 24.
Tube staff, rail workers, cleaners and staff employed on London's bicycle hire scheme are all being paid bonuses of hundreds of pounds.
Unite also announced it will go to the conciliation service Acas on Monday to show its willingness to reopen talks with the bus companies.
A previous meeting at Acas ended without a deal even though London Mayor Boris Johnson announced that £8.3 million was available to pay a bonus to bus staff.
Three firms - Go-Ahead, Arriva and Metroline - obtained a High Court injunction preventing their employees joining the strike.
Unite is re-balloting its members at the three firms for strikes, with the result due on July 17, a week before the second new strike.
Regional officer Peter Kavanagh said: "Strike action is being pushed closer and closer to the Olympics because bus companies, supported by the Mayor, seem to think it is acceptable to try a dangerous game of brinkmanship.
"This dispute could be resolved at a stroke if the operators negotiated meaningfully. Instead it looks like a co-ordinated attack, orchestrated by the Mayor, looking for a political fight with Unite and bus workers.
"The workers are getting angrier by the day, and there will be no retreat."
Unite said that as well as the £500 bonus, it would hold out for an extra £100 for every day the workers go on strike.
Labour leader Ed Miliband told Unite's national conference in Brighton earlier today that the Games should not be disrupted by industrial action.
"We want the Olympics to be a success. The best way to resolve this dispute is by the two sides getting around the negotiating table and negotiate a solution.
"We cannot let industrial action disrupt the Olympics and damage the special moment for Britain. The two sides must make sure that does not happen."
A Downing Street spokeswoman said: "As with all strikes, we hope that a resolution can be found that doesn't involve strike action.
"There is nothing more frustrating for passengers than when they are inconvenienced. We hope for a resolution and that this strike action doesn't need to take place."
Asked whether Prime Minister David Cameron was concerned at the prospect of disruption to the Olympics, the spokeswoman said: "We want these to be the most successful Games and we are confident they will be. We want them to run as smoothly as possible.
"We have been contingency planning and we are prepared. Transport for London have a number of contingency plans in place for various eventualities."
Conservative Party co-chairman Baroness Warsi said: "Labour's biggest funders are clearly hell-bent on disrupting Londoners' summer with unnecessary and unjustified strike action.
"It's time for Ed Miliband to tell Len McCluskey and Unite to call off this strike and Labour must refuse to take any more Unite cash until they do."