LOS ANGELES, July 31, 2008 (AFP) - California said Thursday it planned to sue the US government for failing to regulate greenhouse gas emissions from ships, aircraft, construction and agricultural equipment.

In the latest legal threat from the state against the Environmental Protection Agency, California's Attorney General Jerry Brown said the body was 'wantonly ignoring' its duty to set pollution standards.

California is already suing the EPA over the agency's failure to approve the state's proposed standards for vehicle emissions.

'Ships, aircraft and industrial equipment burn huge quantities of fossil fuel and cause massive greenhouse gas pollution yet President (George W.) Bush stalls with one bureaucratic dodge after another,' Brown said in a statement.

'Because Bush's Environmental Protection Agency continues to wantonly ignore its duty to regulate pollution, California is forced to seek judicial action.'

Brown said under federal law the EPA was authorized to regulate greenhouse gases on ocean-going vessels and aircraft, as well as agricultural, construction and industrial equipment.

However Brown accused the EPA of failing to act to combat pollution from those sources and said California would sue if it failed to enforce regulations within six months.

The lawsuit threat comes one week after Californian environmental regulators approved stringent guidelines aimed at forcing ocean-going vessels visiting the state's ports to use cleaner fuel.

California Governor Arnold Schwarzenegger has made the environment a central plank of his tenure, signing a historic bill in 2006 that saw the state become the first in the United States to impose limits on global warming gases.

Under the plan, California will aim to slash the state's carbon dioxide emissions by 25 percent by the year 2020, a figure that Schwarzenegger has said is equivalent to removing 6.5 million vehicles from the road.