A Kremlin-backed candidate has been elected head of the Donetsk breakaway republic as Moscow cements its control over eastern Ukraine.

Denis Pushilin, acting head of the self-declared Donetsk people's republic, won 61 per cent of the vote in an uncompetitive election on Sunday condemned by the UK and other Western countries.

Leonid Pasechnik, acting head of the neighbouring Luhansk people's republic, which is also backed by Russia, won 68 per cent of a vote there, local authorities said on Monday.

The elections on Sunday were called after the previous leader of the Donetsk separatists was assassinated in August. Mr Pasechnik's predecessor fled to Russia when unmarked troops seized his headquarters in November 2017.

Predominantly Russian-speaking separatists in the Donetsk and Luhansk regions rose up against the new pro-Western government in Ukraine in 2014, sparking a conflict that has killed more than 10,300 people. The two sides shoot at each other across a shrinking buffer zone almost daily despite a 2015 ceasefire.

Moscow's troops helped stop a 2014 Ukrainian offensive to take back the breakaway statelets, and military advisors, arms and funding from across the Russian border have continued to bolster the separatist forces. The Kremlin denies any military role.