Washington - US legislators on Tuesday unveiled far-reaching climate legislation that would boost incentives for renewable energy and for the first time force companies to pay for pollution that is blamed for global warming.

The draft bill, introduced in the Energy and Commerce Committee in the US House of Representatives, marks the first step in what promises to be a long and contentious battle in Congress.

The legislation dovetails with President Barack Obama's pledge to aggressively tackle greenhouse-gas emissions, lowering them by about 15 per cent by 2020 and 80 per cent by 2050. It also comes as world governments are meeting in Bonn, Germany, to start work on a global treaty to tackle global warming.

The US legislation would introduce a cap-and-trade programme, which essentially allocates pollution credits to companies that can then be traded on the open market between cleaner and dirtier firms.

The idea has faced stiff resistance from opposition Republicans, who have derided the measure as a tax on business and a job killer in times of recession. It must first make its way through committees in both the Senate and the House and is not expected to be adopted by Congress before 2010.

Congressman Henry Waxman, the Democratic chair of the committee, billed the draft legislation as an effort to push US businesses to take advantage of opportunities in renewable energy.

"This legislation will create millions of clean energy jobs, put America on the path to energy independence and cut global warming pollution," Waxman said.

Former president George W Bush long resisted imposing mandatory limits on greenhouse-gas emissions. A similar piece of legislation failed in Congress in 2008. (dpa)