Interpol has issued what's called a 'red notice' for Julian Assange, the founder of the Wikileak website.
Interpol says he is wanted for questioning in Sweden over an alleged sex offence, which he has denied.
A 'red notice' does not amount to an arrest warrant. Instead, it asks people to contact the police if they have any information about his whereabouts.
Some of Mr Assange's supporters have accused unnamed forces of framing him for alleged sexual assaults on two Swedish women in order to undermine his campaign to publicise secret documents.
WikiLeaks is under intense pressure after a mass dumping of sensitive American diplomatic cables, which US officials have denounced as a a serious crime and an attack on the whole world.
The BBC reports Mr Assange's whereabouts are unknown. He moves regularly from country to country and is known to have spent periods in Britain and Sweden. He was believed to have been in the UK earlier in November.
It is thought he stays in the same place only for a short period of time.
Mr Assange, 39, filed an appeal with Sweden's Supreme Court in an effort to overturn a ruling by the Stockholm district court earlier this month that he be detained for questioning on allegations of rape, sexual molestation and unlawful coercion, stemming from a visit in August.
His petition was rejected by the Stockholm appeals court last week.
Pakistan 'unconcerned' by Western nuclear worries
Senior government officials in Pakistan have dismissed Western concerns about the security of its nuclear weapons programme, following the publication of more United States diplomatic cables by the WikiLeaks website.
The latest cables show widespread concern about the safety of Pakistan's nuclear weapons, with worries stretching from the United States to Saudi Arabia to Russia.
Pakistan says the nuclear weapons are safe and spent fuel rods in the nuclear reactors are secure.
It says the material has a foolproof control and command system.
