One of the leaders of Russian-backed separatists in east Ukraine, Andrei Purgin, said on Tuesday he had been released from custody after being held in a cell for four days by his own side for reasons he did not understand.
Purgin was arrested last week as part of an apparent power struggle before the breakaway region prepares to hold its own elections. He was detained after being dismissed as head of the separatist parliament, near the rebel stronghold of Donetsk after returning from Russia.
"I've been released. I've been at home for two hours," Purgin told Reuters, saying he had spent the last four days in the rebel security ministry in a good cell. "I haven't figured out what they wanted," he said.
Purgin had been a prominent member of the rebel leadership since separatist unrest erupted in Russian-speaking east Ukraine in April 2014. He had also been a rebel representative in peace talks involving France and Germany.
The spokeswoman for top rebel leader Alexander Zakharchenko declined to comment.
A former head of the rebel parliament's administration was also dismissed and was now wanted by rebel security forces, said Denis Pushilin, who has taken over as the head of the separatist Donetsk parliament.
Moscow, Kiev, Berlin and Paris have called for a truce in east Ukraine from Sept. 1 and the region has been relatively calm in recent days.
The conflict has killed more than 6,500 people in 1 1/2 years.
Ukraine is due to hold regional elections on Oct. 25. Donetsk rebels and their fellow separatists in neighboring Luhansk said they would hold their own votes on Oct. 18 and Nov. 1, respectively, drawing protests from Kiev.
"Purgin was exceptionally independent and had his own political line," said the former head of the rebels' self-proclaimed Donetsk People's Republic, Alexander Borodai, who is a Russian citizen.
Purgin used to be a deputy to Borodai, who moved back to Moscow last summer as Zakharchenko took over in Donetsk.
There was no immediate comment on the developments from Moscow, which sides with the rebels but denies sending them arms or serving Russian troops.
The United States and the European Union slapped sanctions on Russia over the conflict, which dragged ties between Moscow and the West to post-Cold War lows.