The US vice-president, Dick Cheney, was behind a controversial decision to block California's attempt to impose tough emission limits on car manufacturers, according to insiders at the government Environmental Protection Agency.

Staff at the agency, which announced last week that California's proposed limits were redundant, said the agency's chief went against their expert advice after car executives met Cheney, and a Chrysler executive delivered a letter to the EPA saying why the state should not be allowed to regulate greenhouse gases.