Chief executives from the US Climate Action Partnership (USCAP), a coalition of nine of the largest companies in the US, are imploring President Bush to begin tackling global warming.

They believe Bush should support a mandatory cap on greenhouse gas emissions.

Bush will address the issue in his State of the Union speech today, but will not introduce binding rules for emissions, says a White House statement.

"We can and must take prompt action to establish a co-ordinated, economy-wide market-driven approach to climate protection," the executives said in a letter to President Bush.

The groups want to push for mandatory caps on greenhouse gases to cut them by more than 60% by 2050.

Members of USCAP are CEOs of Duke Energy, Alcoa, BP America, DuPont, Caterpillar, General Electric, Lehman Brothers, FPL Group and PG and E.

Currently there is widespread confusion in the US over emission caps - some states impose them and some don’t and the limits vary.

Although The White House said Bush was going to make an ‘important announcement’ about energy efficiency and greenhouse gases, his press secretary Tony Snow said "binding economy-wide carbon caps" are not part of Bush's approach.

He added that the president believed that industry must come up with innovations to address the issue of climate change, but how closely he is prepared to guide this notion is currently unclear.

In the past Bush has always rejected mandatory controls on greenhouse gases.

The US withdrew from the Kyoto protocol in 2001.