Former Chechen President Zelimkhan
Yanderbiyev has been killed in an explosion in Qatar.
Russia had been seeking Mr Yanderbiyev's extradition
The satellite TV station al-Jazeera said Mr Yanderbiyev's car was hit by a blast in the capital Doha.
Two of his bodyguards were reportedly killed in the blast and Mr Yanderbiyev was taken to hospital for treatment but died of his wounds soon afterwards.
He was mentioned on a UN list of groups and people with suspected links to the al-Qaeda organisation.
Mr Yanderbiyev was acting Chechen president in 1996.
He headed the rebel delegation which held talks with Russian President Boris Yeltsin and Prime
Minister Viktor Chernomyrdin in the same year.
He has been included on the Interpol wanted list since 2001.
The former Chechen leader was living in Qatar for three years and Moscow repeatedly sought his extradition.
He was viewed as a key figure behind the 1999 Chechen invasion of Dagestan.
He was also suspected of links to the siege of a Moscow theatre in October 2002 that left 130 hostages dead.
Mr Yanderbiyev was considered a key link in the Chechen rebels' fundraising network from abroad.