Tokyo and its surrounding areas are planning to clamp down on diesel emissions in a bid to cut the level of pollution in the region.

Governor Shintaro Ishihara, who successfully campaigned on the issue of pollution, has now written to the Japanese Prime Minister Junichiro Koizumi alleging his government has failed to live up to his promises on pollution.

Mr Ishihara has even threatened to sue the Government for not delivering on pledges to tackle emissions.

Now the Tokyo city government hopes new regulations on diesel-powered commercial vehicles will dramatically cut particulate emissions in the city to 1,600 tons-a-year from 4,300 tons in 2000.

'Basically, if your vehicle does not comply with the regulations, you must either buy a new one or fit a device that will bring it in line with the rules,' Hiroaki Furuta of the city government's pollution control department told Reuters.

Owners of some trucks are expected to face fines of up to 500,000 yen unless they manage to cut their emissions.