Doku Umarov, the head of Chechnya's armed separatist group, has withdrawn comments that he is stepping down from his post, according to a video broadcast online.
"Due to the situation in the Caucasus I consider that it is impossible for me to quit my duties," he was shown saying in a posting on Kavkazcenter.com, a separatist website, on Wednesday.
"The previous declaration is annulled. It is a falsification," he said.
A video posted earlier this week appeared to show Umarov, 46, citing health reasons for stepping down to make way for a "more energetic" successor.
But in the new video he said: "I declare that my health is good to serve Allah.
"And I will serve the word of Allah and work to kill the enemies of Allah in all the time that he gives me to live on this earth".
Kavkazcentre.com added that Umarov had described the earlier video, first released on Sunday, as a "fabrication", but offered no explanation on the two differing statements.
Umarov describes himself as the emir of the Caucasus Emirate - a separatist group fighting for independence in Russia's predominantly Muslim North Caucasus, to create a state governed by sharia (Islamic law).
Also known as Abu Usman, Umarov has for years been at the centre of the rebellion in the Caucasus, which has claimed scores of lives annually.
He joined Chechnya's separatists in 1992, fighting in both Chechen wars against Russian forces, and also served as security minister in the province's separatists government from 1996 to 1999.
Umarov claimed responsibility for twin suicide bombings that killed 40 people on Moscow's metro in March and the derailment of a Moscow-St Petersburg train that left 26 people dead in November last year.
He is believed to have been wounded several times in recent years, causing some speculation over whether the rebel leader is still alive.
Russian authorities have prematurely announced his death on a number of occasions.
His separatist movement has evolved from one seeking independence from Moscow to a broader Islamic movement looking to establish an Emirate across the Caucasus mountains.
Last month, the Chechen rebels attacked a hydroelectric plant in the North Caucasus republic of Kabardino-Balkaria, signalling a change in their tactics and making good on a pledge made long ago to attack Russia's economic interests.
The United States has listed Umarov, who is also Russia's most-wanted man, as a terrorist.