It said less than a third of Londoners would oppose such a policy.The survey, carried out by YouGov, also indicated that more than two thirds of Londoners think higher polluting vehicles should pay more than other vehicles travelling through London.
The group said the findings will heap pressure on the next London mayor to switch more quickly from diesel buses to cleaner electric and hybrid models used in electric mode.
Similarly, 54% said diesel taxis should be stopped from operating in the city centre, and 52% backed a ban on all diesel cars.
ClientEarth lawyer Alan Andrews said: Londons air is toxic and illegal. We know that we need more ambitious policies if our polluted air is to be cleaned up and this survey shows the next Mayor will have clear public backing if they introduce bold policies.
Londoners have had enough of dirty air and they want their mayor to get tough on the dirtiest vehicles. If the mayoral candidates are smart they will listen and show some courage. The time for excuses is over.
Last month outgoing mayor Boris Johnson said his successor would have to consider increasing thecharge to tackle rising traffic levels.
Source: Transport Network