Image copyright AP Image caption The prospects for the bill in the Senate are unclear

The US House of Representatives has passed a bill to approve the controversial Keystone XL oil pipeline.

The legislation will now be put to a vote in the Senate next week, where its prospects are unclear.

The 875-mile (1,408km) pipeline would carry tar sands oil from Alberta, Canada, to the US state of Nebraska where it joins pipes running to Texas.

President Barack Obama is said to take a "dim view" of the legislation, but has not directly threatened a veto.

The project has pitted Republicans and other supporters, who say it will create much needed jobs, against many Democrats and environmentalists, who warn the pipeline will add to carbon emissions and contribute to global warming.

A state department report raised no major environmental objections in February, but the final recommendation was delayed amid a court battle over the project in Nebraska.

Image copyright Getty Images Image caption Keystone XL has been criticised by environmental groups

The state department is involved because the pipeline would cross an international border.

The Keystone XL pipeline aims to carry some 830,000 barrels of heavy crude a day from the fields in Alberta to Nebraska.

The oil would then be transported on existing pipes to refineries in Texas. The southern section of the project was finished last year.

"At some point, President Obama has to realise that his blockade of the Keystone XL pipeline is forcing American consumers to depend on volatile oil-rich regimes and is hurting our diplomatic relationship with our top trading partner - Canada," House Foreign Affairs committee chairman Ed Royce said in a statement.

The bill passed easily with a 252-161 vote, but it was not the first time the House had voted to approve the project.

However, the latest vote stands the best chance in six years of making its way to Mr Obama's desk.

Image copyright Reuters Image caption Democratic senators Mary Landrieu, Joe Manchin and Heidi Heitkamp (l-r) have broken ranks to support the pipeline

The bill's sponsor, Louisiana Representative Bill Cassidy, is facing a run-off election against incumbent Democratic Senator Mary Landrieu for her seat.

Ms Landrieu - among the pipeline's Democratic supporters - successfully pushed the Senate to hold the vote on the measure on Tuesday.

Supporters of the measure say they are confident they have the 60 votes, including several Democrats, needed for passage of the bill.

Speaking in Myanmar on Friday, Mr Obama said the full review of the project cannot be finished until the Nebraska lawsuit is resolved.

"I don't think we should short-circuit that process," Mr Obama said. The president has previously threatened to veto similar bills.