All ocean-going vessels within 24 nautical miles of California’s coastline must use cleaner burning diesel fuel, under new state regulations.

The regulations aim to reduce SOx, NOx and diesel emissions, California’s Governor Arnold Schwarzenegger said.

Vessels will also have to use lower-sulphur marine distillates rather than highly polluting heavy-fuel oil or bunker fuel.

The laws, adopted by the California Environmental Protection Agency, will affect around 2,000 ocean-going vessels visiting California annually.

The move will initially reduce emissions of toxic particulate matter from vessels by 13t a day, according to the government.