Transport for London and the mayor's office are putting plans for around 60 hydrogen fuel cell vehicles on hold, providing fresh ammunition for green groups which claim Boris Johnson's environmental record has failed to live up to his pre-election pledges.

TfL released a statement earlier today claiming that a plan to "seed the market" for hydrogen-powered vehicles in London has been shelved due in part to a poor response from vehicle manufacturers.

"The key objectives of the project were not met. We were looking for original equipment manufacturers to produce these hydrogen vehicles from the beginning," said a TfL spokeswoman.

"We turned out to be a bit before our time on this one. We not saying it is dead forever. We will be looking at the market in a year or two and perhaps the current fuel crisis may mean more manufacturers will be looking to develop these kind of vehicles," she said.

The original scheme, announced in February 2006 under London's previous mayor Ken Livingstone, aimed to introduce 70 new hydrogen vehicles to London by 2010.

Around 10 of the hydrogen-powered vehicles were buses and TfL confirmed investment in this aspect of the project will continue. "This decision does not affect the hydrogen bus project, of which 10 vehicles will begin operating by 2010, as planned," the spokeswoman explained.

"We will continue to monitor the development of the hydrogen-vehicle market and review opportunities to support the introduction of hydrogen-fuelled vehicles in London once the bus refuelling site is operational," she added.

Funding for the other 60 vehicles, which would have included motorbikes, vans and cars for use by the Metropolitan Police, and the Fire Brigade, among others, will be suspended.

TfL claims the project was an attempt to try to "seed the market" for hyrdogen-powered vehicles in London by leasing the vehicles to other agencies to encourage uptake of the technology in the public and private sectors.

The hydrogen vehicles project was to have cost £4 million, funded from TfL's Climate Change Action Fund. The money saved will be directed to other climate change programmes, TfL claimed.

The U-turn over fuel cell investment comes amid criticism of mayor Johnson's environmental record during his first 100 days in the job. Friends of the Earth issued a statement yesterday claiming that although Johnson has retained his predecessor's commitment to cut carbon emissions in the capital by 60 per cent by 2050, he has not said how this will be achieved.

"Boris has made some good policy statements but he has not shown how he is going to follow through," said Friends of the Earth London campaigner Jennifer Bates. "He has adopted Ken's climate change reduction targets but Ken backed it up with an action plan. Boris hasn't endorsed that action plan or come up with another one."

According to Friends of the Earth, Johnson has also initiated several measures that are taking London in the " wrong direction", including scrapping plans to introduce an emissions-related congestion charge for London and re-opening the public consultation on last year's western extension of the original charging zone.

The lobby group has also criticised the mayor's support for an extra river crossing downstream from Tower Bridge to ease traffic congestion, which it claimed could actually lead to a rise in the number of vehicles on London's roads. According to Bates, Johnson originally said he was opposed to the Bridge scheme but has subsequently shifted his position to one of "not ruling out" construction.

"New road space fills with new traffic and a new bridge bringing traffic into London would encourage more traffic and increase congestion in the long term - he doesn't seem to have grasped that fact," she said.

The mayor's handling of traffic congestion in London was also criticised earlier this week after TfL admitted in a report that congestion in London's congestion charge zone was now as bad as it had been in February 2003 before the charge was introduced.

The return to pre-Congestion Charge levels was put down to a reduction in road space resulting from increased road works and more allocation of space to bikes and buses.

Malcolm Murray-Clark, managing director of planning for TfL, said that without the Congestion Charge the traffic problems in London would be much worse.

"However, as a result of other interventions such as utility and construction works, the reduction in road space has had a detrimental impact on congestion levels and is slowing traffic down," he said in a statement.