Bus services in London were disrupted after a series of protests today by workers involved in a row over an Olympic bonus payment, amid warnings of fresh strikes.
Unite called on bus operators and Transport for London (TfL) to resume talks over a claim for a £500 bonus or face further walkouts.
The union announced it will re-ballot its members in the three bus companies who were prevented from taking part in last Friday's strike because of a court injunction.
Voting among 4,000 bus workers working for Metroline, Arriva the Shires and Go Ahead London General will be held in the next few weeks.
A TfL spokesman said: "Protesters at five bus garages caused disruption to 33 bus services this morning. The Metropolitan Police were called in each case and all buses have now resumed passenger service.
"The payment of bus staff for the Olympic and Paralympic Games is a matter for the private companies who employ them. Any disruption to transport services for Londoners is simply deplorable especially in circumstances where the employers' offer has not even been put to the bus workers themselves."
Hundreds of workers employed on London's bike hire service are set to receive a £500 bonus for working during the Olympics.
The Community union said its 220 members on the so-called Boris Bike scheme - named after the capital's Mayor Boris Johnson - will also get improved overtime payments in recognition of their increased workload during the Games.
Unite's London regional secretary Peter Kavanagh said: "TfL and the bus operators need to get back around the table. Their refusal to meaningfully negotiate an Olympic award for keeping London moving during the Olympics is unjustifiable. Even the people who work on the Boris bikes have today been handed on a plate, a bonus of £500, demonstrating further the contempt the Mayor holds for the 28,000 bus workers he once described as the world's finest.
"This is a straightforward industrial issue about fairness and recognition. It is now looking more and more like a co-ordinated attack by the Tory Mayor, supported by a party looking for a political fight with Unite and London's bus workers.
"TfL and the bus companies should be under no illusion of our resolve. We are re-balloting our members in the three bus companies who were stopped by the courts from exercising their democratic rights last Friday. This will mean that future strike action will be bigger and involve more bus workers. TfL and the bus operators need to take their heads out of the sand and recognise the massive increase in work that bus workers will face during the Games."