Britain's Supreme Court has upheld the extradition of WikiLeaks founder Julian Assange to Sweden over alleged sex crimes.

Seven judges at the country's highest court rejected by a majority of 5-2 that Mr Assange's claim that a European Arrest Warrant under which his extradition is sought was invalid. Two lower courts have already ruled he should be extradited.

The 40-year-old is sought for questioning on sex crimes allegations relating to accusations made by two Swedish women after he visited Sweden in 2010. He denies the charges.

Mr Assange can appeal to the European Court of Human Rights. The ECHR must respond within 14 days to indicate whether or not it will accept the case.

The WikiLeaks founder has been fighting a lengthy legal battle against extradition since his arrest in Britain in December 2010.

Since his detention, he has mostly been living under strict bail conditions at the country mansion of a wealthy supporter in eastern England.

Mr Assange gained international prominence in 2010 when WikiLeaks began releasing secret video footage and thousands of US diplomatic cables about Iraq and Afghanistan, in the largest leak of classified documents in US history.

That brought him to the attention of Washington and other governments who accused Mr Assange of putting lives at risk by blowing the cover of sources who spoke to diplomats and intelligence agents in countries where it was dangerous to do so.