British Prime Minister Gordon Brown causes more greenhouse-gas emissions than three other major European leaders, according to a report in Terra Eco, a French environmental monthly.

Last year Mr Brown emitted more than 8,400 tonnes of carbon dioxide (CO2) or its equivalent on official trips, it said.

German Chancellor Angela Merkel was second, with 7,400 tonnes, followed by French President Nicolas Sarkozy, 7,100 tonnes and Spanish Prime Minister José Luis Rodriguez Zapatero, with 6,700 tonnes.

Mr Sarkozy flew 324,000 kilometres, compared with 175,000 kilometres each for Mr Zapatero and Ms Merkel and 158,000 kilometres for Mr Brown.

Mr Brown, though, caused more carbon pollution because he flies in larger or less fuel-efficient jets, according to Terra Eco's calculations.

Mr Sarkozy flies in an Airbus A 319, Ms Merkel in an A310 and Mr Zapatero in an A310 and Super Puma.

Downing Street declined to say what type of aircraft is used by Mr Brown, citing security reasons, Terra Eco said.

Based on information from other journalists and aviation experts, the monthly magazine made its calculations in the belief that he uses a mix of Boeing 747, 757 and 777.

By way of comparison, a large saloon car of average fuel efficiency emits around five tonnes of CO2 per year, based on a distance of 20,000 kilometres.