By David Bamford BBC News

Mr Yanderbiyev spent the last three years in exile in Qatar

A 51-year-old Islamist who wrote ideological poetry, Zelimkhan Yanderbiyev rose to prominence in the early 1990s when Chechnya broke away from Russia.

He became deputy to the separatist leader, Dzhokhar Dudayev.

When Mr Dudayev was killed during fighting in 1996, Mr Yanderbiyev was briefly hustled in as Chechen leader.

He took part in negotiations with Russian President Boris Yeltsin that produced an autonomy agreement, though it soon fell apart.

Elections in Chechnya a few weeks later saw the emergence of a new leader, Aslan Maskhadov.

In the murky world of Chechen politics, Mr Yanderbiyev sided with Islamist factions opposing him.

Chechen rebel representative

Mr Yanderbiyev was widely assumed to have played an important role in a campaign of armed incursions into Dagestan in 1999.

Forced out of the region by Russia's military invasion, he became Chechen rebel representative in the Gulf and Muslim states.

He had lived in Qatar for the last three years, touring the Muslim world seeking funds for the Chechen cause and setting up a Chechen embassy in Afghanistan, prior to the fall of the Taleban regime in 2001.

Russia called for his extradition, accusing him of helping to co-ordinate Chechen suicide attacks from Qatar, including the seizure of 800 hostages in a Moscow theatre on October 2002.

The Russian security agency said that during the siege the hostage takers spoke by telephone to Mr Yanderbiyev.

One hundred and thirty hostages died during the Russian rescue attempt.

US security agencies also long suspected Mr Yanderbiyev of playing a key role in directing from the Gulf states funding linked to al-Qaeda, to support a rebel Chechen faction dubbed the 'Islamic regiment'.

Even fellow Chechens condemned the faction for its strategy of suicide bombings and atrocities against Russian civilian targets.

Mr Maskhadov has stated his opposition to suicide attacks.