An energy bill that raises the fuel efficiency of vehicles on US roads for the first time in 32 years passed the Senate on Thursday, after backers bowed to White House pressure and dropped higher taxes on oil and gas companies.

Also dropped were provisions that would force power companies to buy some of their electricity from renewable sources. The concessions brought President George W Bush's Republicans on board for the landmark bill, which passed 86-8.

Senator Harry Reid, the Democratic leader in the upper chamber, called it "a small first step in our fight to turn the tide of global warming."

But he voiced disappointment that Republican opposition had derailed a Democratic effort to reduce tax breaks for big oil and use the money to spur investment in clean energy.

The House of Representatives is expected to take up the bill next week. The White House had threatened to veto the provisions for utilities and the oil industry, but said Bush would approve the revised version.

"If this legislation makes it to the president's desk, he will sign it into law," White House spokeswoman Dana Perino said.

Current US standards for cars oblige automakers to have fleet average of 27.5 miles per gallon (8.6 litres per 100 km) of fuel use. Under the new proposal, that would rise to 35 miles per gallon (6.7 litres per 100 km) by 2020.