THE elusive head of whistle-blower website WikiLeaks, Julian Assange, has been arrested by British police in relation to an international warrant issued by Sweden over alleged sex offences there.

A fresh European arrest warrant was received by Mr Assange's British lawyer Mark Stephens yesterday.

Sky News sources said officers from Scotland Yard detained the 39-year-old Australian about 9.30am local time (9.30pm AEDT) by appointment at a London police station.

A Metropolitan Police statement said he was "accused by the Swedish authorities of one count of unlawful coercion, two counts of sexual molestation and one count of rape, all alleged to have been committed in August 2010." Mr Assange denies the claims.

Labelling the move as a "political stunt," Mr Stephens said Mr Assange wanted to find out what allegations he faces so he can clear his name.

He was due to appear at the City of Westminster magistrates court in central London later Tuesday (overnight AEDT) so a decision can be made about whether the warrant is appropriate for extradition.

Read more about WikiLeaks founder Julian Assange's arrest at Sky News.