Chechen rebels have named the successor to leader Aslan Maskhadov, killed in a Russian raid on Tuesday.
Maskhadov's family has appealed to the West to help return his body
The influential radical warlord Shamil Basayev said Abdul-Khalim Saydullayev, head of the rebels' so-called Sharia court, would take over until elections.
Officials close to Maskhadov later confirmed the succession of Mr Saydullayev, a little-known cleric, following a decree signed last year.
Meanwhile the dead leader's family has appealed for the return of his body.
Maskhadov's widow, son and daughter made an impassioned plea to the international community to pressure Russian President Vladimir Putin into releasing his remains.
"Under the pretext that the slain legitimate president Maskhadov was a so-called terrorist, the Russian leadership is not releasing his body for burial," the family said.
Their plea came in a letter read out at a memorial service in the Azerbaijani capital Baku on Thursday.
"That way, the pain of our loss is compounded. This is blasphemous and completely inexplicable in a modern civilised world."
Maskhadov was killed in a special operation by Russia's security services in the village of Tolstoy-Yurt near the regional capital, Grozny.
According to officials the body will be buried in an unmarked grave.
In a message posted on the rebel Kavkaz Center website, Mr Basayev, who has claimed responsibility for the Beslan attack and the 2002 Moscow theatre siege, called on the rebels to continue their campaign against Russia.
He said Maskhadov had decreed that the head of the Sharia court would take over as caretaker in the event of his death.
A rival website later carried a similar message from Akhmed Zakayev, Maskhadov's representative in the UK.
Mr Saydullayev has been described as an expert on Islam and Sharia law, but there is some confusion about his origins and identity.
The Russian gazeta.ru website, quoting Russian intelligence services, says he is a Saudi national who came to prominence in the rebel movement in 2002 because he was able to bring funds to the movement.
Other sources, including Maskhadov's son, describe him as a native of the Chechen village of Stariye Atagi.
Several pro-Moscow Chechen officials said they did not know who he was and suggested he might be a fictitious figure or a puppet of Mr Basayev.
Mr Basayev and another field commander Doku Umarov are considered the most powerful rebel commanders and had been seen as possible candidates themselves.
It is unclear if Maskhadov's killing will boost Russia's grip in Chechnya, experts say.
Maskhadov, who was elected president of Chechnya in 1997, was seen as the most moderate of Chechnya's rebel leaders, analysts say, though Moscow blamed him for several major attacks.