The mayor wants a cleaner bus for London
London's mayor has said the capital will be the greenest city on earth by the time of the 2012 Olympic Games.
Boris Johnson said London was committed to reducing CO2 emissions in the city by 60% by 2025.
He told a meeting in South Korea of the leaders of the world's 40 largest cities that one idea was to push ahead with cycle super-highways.
But the London Assembly Green Party said the mayor's policies are making London dirtier and more polluted.
Leaders of the world's largest cities are meeting in Seoul this week for the C40 climate change conference.
Mr Johnson said London wants to use the Olympics to make it the "cleanest, greenest city on earth."
The mayor said the key measure was addressing the problems relating to domestic and commercial buildings, which accounted for 70% of CO2 emissions in London.
This involved installing lagging in large numbers of public buildings.
Mr Johnson described himself as a "passionate cyclist" and said he would push ahead with cycle super-highways around London.
He also called for "real progress" by cities worldwide towards the electrification of it its fleets of vehicles.
London's air quality problem, he said, was caused by vehicle emissions from 8,300 old diesel buses which could be replaced by low-carbon vehicles.
There were also 32,000 taxis running on diesel fuel which could be replaced by electric vehicles.
Johnson said there would be a major push in the next few years to produce a "cleaner, greener" bus for his city.
Darren Johnson, leader of the London Assembly Green Party, said: "The London mayor might say he wants a cleaner, greener city, but his policies are actually making London a dirtier and more polluted city.
"He cancelled the £25 charge on gas guzzlers, suspended tighter regulation of 90,000 of the most polluting vans and is planning to ditch the western extension of the congestion charge.
"The mayor is also failing to deliver on his own plans with a £13m under-spend on the environment last year, no commitment to build a carbon free Olympic village and the knowledge that electric vehicles will make little impact by 2012."