Obama congratulates Cameron on UK election

US President Barack Obama has congratulated David Cameron on an "impressive electoral victory," after the British prime minister secured a new term in power.

"The special and essential relationship between the United States and the United Kingdom is rooted in deep and abiding shared interests and values," Obama said in a statement on Friday.

"I have enjoyed working closely with Prime Minister Cameron on a range of shared interests these last several years, and I look forward to continuing to strengthen the bonds between our countries."

Cameron's Conservative party won victory, despite widespread predictions of a tie with the Labour party.

Cameron has promised to hold a referendum on Britain's European Union membership in 2017, a vote that could have profound repercussions for the country's role on the world stage.