London bus drivers will stage fresh strikes in July, including one days before the start of the Olympics, in a dispute over extra payments during the Games, a union said last week.

Thousands of bus workers in the British capital plan to strike on July 5 and July 24, the Unite union said, threatening severe disruption to services ahead of the Games, which open on July 27.

Bus drivers are asking for a bonus in recognition of the extra workload they will face during the event, after rail, Underground and airport workers were promised extra remuneration.

The workers went on strike on June 22, causing travel chaos for tens of thousands of passengers, and union leaders warned that further strikes could bring London to a standstill.

Three bus companies obtained a High Court injunction preventing their employees joining that strike but Unite says it is re-balloting its members at the firms over the latest action.

The union is seeking a bonus of £500 for its 21 000 members at 20 firms.

It accused bus operators of playing "a dangerous game of brinkmanship", claiming that their failure to meet the demands of bus workers was pushing strike action closer to the Games.

"Last week's action was extremely well supported and workers are getting angrier by the day - there will be no retreat," said Unite regional secretary Peter Kavanagh said.

"Bus services could come to a total standstill just days before the Olympics if bus operators continue to turn their backs on their workers."

Unite urged bus operators to join talks on Monday with Britain's ACAS conciliation service.

Previous talks at ACAS ended without a deal despite an announcement from London Mayor Boris Johnson that £8.3-million was available to reward bus staff.