WikiLeaks founder Julian Assange handed himself in to British police on Tuesday after Sweden issued a warrant for his arrest over allegations of sex crimes, London's Metropolitan Police said.

Assange, whose WikiLeaks website is at the center of a row over the release of secret U.S. diplomatic cables, was arrested under a European Arrest Warrant.Swedish prosecutors want to question the 39-year-old Australian about allegations of rape, sexual molestation and unlawful coercion. He denies the allegations.

Assange is due to appear before City of Westminster Magistrates' Court in London later on Tuesday when a date for an extradition hearing is likely to be set. This must take place within 21 days of his arrest.

"He is 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," London police said in a statement.

Assange has spent much of his time in Sweden and earlier this year was accused of sexual misconduct by two female Swedish WikiLeaks volunteers.

This led Swedish prosecutors to open, then drop, then re-open an investigation into the allegations. The crime he is suspected of is the least severe of three categories of rape, carrying a maximum of four years in jail.

Police said Assange was arrested by officers from its extradition unit at about 9.30 a.m. (0930 GMT) after he appeared by appointment at a London police station.

His whereabouts had been previously undisclosed.

If a judge is satisfied his extradition is warranted and will not breach his human rights, then he will order the WikiLeaks founder to be extradited, although Assange can appeal against that decision to higher courts.

Assange's Swedish lawyer has said his client would fight any extradition and believed foreign powers were influencing Sweden.

WikiLeaks has angered the U.S. government and others across the world by releasing details of 250,000 diplomatic cables it had obtained.