The new £25 congestion charge will increase CO2 by 182,000 tonnes in London, according to an unreleased Transport for London (TfL) report.

By 2012, CO2 increase in outer London will increase by nearly 184,000 tonnes, while 2,200 tonnes will be saved in central London, giving a net increase of 182,000 tonnes.

The report indicates that the increase is largely caused by increased car mileage outside of the congestion charging zone as a result of the new charge.

According to Porsche, which has launched High Court action against the congestion charge, the TfL-commissioned research from King’s College was never publicly released and only discovered following a specific request.

Its findings directly contradict claims made by mayor Ken Livingstone and TfL.

All figures previously publicly released by TfL with regard to the impact of the new charge on CO2 emissions related only to the position within the congestion charge zone. It has never released estimates taking into account the effect on the whole of Greater London.

Andy Goss, Porsche GB managing director, said: “We always knew the environmental impact of this unfair tax would be minimal, now we know it will make matters worse.

“The Mayor and TfL need to explain why this report was not disclosed and why they want to increase taxes on motorist that will increase CO2.”