A 24-hour London bus strike has begun following the collapse of peace talks in a dispute over Olympics payments.

The walkout by thousands of members of Unite at 17 bus companies in pursuit of a £500 payment for working during the Games will hit most parts of London, disrupting travel for commuters and tourists.

Transport for London (TfL) said, however, that more than a third of bus services were running. These are mainly in central, south and north-west London after a high court judge granted an injunction on behalf of three operators. It is understood that around 85% of the total workforce is on strike.

Despite the injunction, Unite said thousands of bus workers would stage the first city-wide walkout since 1982, after peace talks at the Acas conciliation service failed. It said strikes by staff at the 17 remaining operators would go ahead because they were not affected by the injunction over balloting anomalies.

Unite's regional officer, Peter Kavanagh, said bus operators were "refusing to enter into genuine and timely negotiations" over Unite's demands that bus workers receive a £500 payment in line with their peers on the London Underground, London Overground and Docklands Light Railway networks.

Warning that strikes during the Games were possible, he said: "If the operators shirk their responsibilities now they will sow the seeds of massive anger and frustration across the bus network, inevitably leading to strife and industrial action during and way beyond the Olympic Games."

London bus operators said in a statement that they had put together a package that would have awarded bus workers £500 each if they worked throughout the 29 days of the Olympics and Paralympics – a shift pattern that Unite dismissed as impossible.

"Unite's demand, which includes paying a bonus to staff irrespective of whether they are working over this period, would amount to over £20m," said the operators. The main source of funding was an £8.3m payment from the Olympic Delivery Authority, which bus operators now fear will be withdrawn by the London mayor, Boris Johnson. "We are fearful that the additional money made available by the ODA has now been lost. We can only apologise for the disruption that will be caused to bus passengers," the companies said.

At West Ham bus depot, a few miles from the Olympic stadium, striking bus drivers said they would take industrial action during the Games if they had to. Speaking anonymously, one said: "We don't want to do that, but we feel like we have been pushed around." Another driver said employees deserved similar Games payments to colleagues at London Underground, London Overground and the Docklands Light Railway, who will be paid between £500 and £900. "We don't want to go on strike but we have got no choice but to resort to this, to point out to Transport for London that we do the same work as our colleagues in other transport departments and we should be paid for it," the driver said.

The Unite shop steward at West Ham depot, Ismael Kanu, 48, said TfL's refusal to match the tube, overground and DLR payments was disrespectful to bus workers. "We are just asking for our own reward," said Kanu, a London bus employee for 27 years. Asked if he was prepared to strike during the Games, he said: "If that's what it takes, yes, we will strike during the Games." The West Ham depot serves eight routes that go via the stadium, but was inactive on Friday morning, with only a dozen buses leaving since the strike began at 3am.

Drivers at the depot, which is run by Stagecoach, also disputed TfL's claim that the bus network would not be as overloaded as the tube or DLR during the Games. "As soon as the underground is overcrowded, it is bus drivers who pick up the pieces," said one driver. Another added: "We deal with passengers face-to-face, the aggro. We should be rewarded for that because I am sure we are going to get more of that [during the Games]."

Kanu added that drivers would not accept TfL's offer of a bonus for drivers on routes directly linked to the Olympics, in effect ruling out a bonus for drivers in the outer boroughs. "It's totally wrong. We are fighting for workers in London as a whole. The tourists coming to watch the Games will be everywhere around London."

Talks to avert the strike broke down despite the intervention of Johnson, who has secured £8.3m from the ODA to help settle the dispute. Unite's demands required a further £6m from the bus operators, the ODA and TfL, although operators now claim that number would have to be doubled.

Johnson said: "It seems to me that some militant union leaders remain hell-bent on strike action, and that is wholly unacceptable. I want the people of London and our honest and hard-working bus drivers to know that we've gone the extra mile, money is on the table, this offer is fair, but it is also conditional on drivers not taking strike action."

Bus operators, who are paid a set fee for running services in London, insist that they could not afford to meet Unite's demands without a subsidy from TfL, which in turn argued that the dispute had to be settled by Unite and the operators.

Peter Hendy, the transport commissioner, said: "It is now clear that the leadership of Unite were intent on a strike all along. They have pursued this unnecessary course of action despite an extra £8.3m being brokered by the mayor that would allow every bus driver in London in a garage where one or more routes were affected by the 2012 Games to gain, over the 29 days of the competitions, about £500."

He added: "We are now working together with our partners to ensure that Londoners and visitors have alternative travel options and the necessary advice to enable them to get around. I would advise everybody to use other transport services, to consider walking and cycling for shorter journeys and to check before travelling at www.tfl.gov.uk/buses."

The capital's bus network carries more than 6 million passengers on a weekday, compared with 3.5 million on the tube. TfL has accused Unite of "attempting to exploit the Games spirit and add a further multimillion-pound burden to the hard-pressed fare and taxpayers of London".