Ukraine's President Petro Poroshenko has dismissed a leadership vote held by rebels in the war-torn east as a sham and called on Moscow not to recognise the outcome.
The polls closed late on Sunday in elections condemned by Kiev and Western governments but backed by Russia.
Alexander Zakharchenko, the main rebel leader in Ukraine's largest separatist region Donetsk, won the controversial election, according to an exit poll conducted by the pro-Russia separatists.
Zakharchenko, prime minister of the self-declared Donetsk People's Republic, was on course to claim 81.37 percent of the vote in the presidential poll, rebel election chief Roman Lyagin said.
The farce that is being conducted under the threat of tanks and guns by the two terrorist organisations in parts of Donbass is a terrible event that has nothing to do with the real will.
His party was also set to claim 65 percent of the parliamentary vote.
"The farce that is being conducted under the threat of tanks and guns by the two terrorist organisations in parts of Donbass is a terrible event that has nothing to do with the real will," Poroshenko said in a statement on Sunday.
The vote was held as Ukrainian claims of "intensive" troop movements across the Russian border cast new doubts over a truce.
The elections in both Donetsk and the Luhansk People's Republic, were billed as bringing a degree of legitimacy to the makeshift pro-Russian authorities already in control.
Zakharchenko had said that the elections would pave the way for improving the economy in the region by allowing it to form trade ties, Al Jazeera's Hoda Abdel-Hamid, reporting from Donetsk, said.
She said the regions have been struggling under the weight of conflict, with many citizens left homeless, living in bunkers, and facing an approaching harsh winter.
"Certainly even though it will become a very young government as they put it they will have some very serious situations to deal with quite urgently," she said.
The polls have deepened an international crisis over the conflict and further undercut an already teetering September 5 truce between Ukraine's government and the heavily armed separatists.
No international election monitors were present for the vote, and no minimum turnout had been set by the organisers, reflecting the uncertainty over how many voters would bother turning out.
The run-up to the polls saw a spate of shelling by rebels of government positions across the conflict zone, where according to UN figures more than 4,000 people have died since fighting started around seven months ago.
Ukrainian authorities announced on Sunday that three soldiers had been killed and seven more wounded, adding to Saturday's toll of seven dead and at least six wounded.
The Ukrainian military also claimed it had detected "intensive" movement of troops and equipment "from the territory of the Russian Federation".
The reported deployments, which would constitute a major escalation of Russian involvement, could not be verified.
Source: Al Jazeera and agencies