Pro-Russian gunmen guard Alexander Zakharchenko (C), Prime Minister of the self-proclaimed Donetsk Peoples Republic and presidential candidate

Russia endorsed a crushing victory for Ukraine’s pro-Moscow rebel leadership after controversial polls on Sunday that the EU slammed as a “new obstacle” for peace in the country’s strife-torn east.

The swift acceptance of the results by Russia looked certain to spark a diplomatic firestorm, with a fresh round of Western sanctions against the Kremlin now increasingly on the cards.

“We respect the expression of the will of the residents of southeast (Ukraine),” the Russian foreign ministry said in a statement, cited by local news agencies.

“Those elected have received a mandate to resolve the practical issues of re-establishing normal life in the region.”

Just prior to Moscow’s announcement, the European Union’s top diplomat Federica Mogherini had already decried the separatist vote as a “new obstacle on the path to peace”.

Ukrainian President Petro Poroshenko blasted the ballot as a “farce that is being conducted under the threat of tanks and guns”. The fear is they could now spell the end for a battered two-month ceasefire between government troops and rebel fighters.

The emboldened rebel leadership in the two separatist enclaves appeared in little mood for compromise after their victories were confirmed.

“Ukraine does not want peace, as it claims. Obviously it is playing a double game,” the newly elected president of the self-proclaimed Donetsk People’s Republic, Alexander Zakharchenko, told journalists.

Zakharchenko, already the undisputed leader in Donetsk, took 81 percent of the vote according to rebel election officials, against nine percent each for his two opponents.

In neighbouring Lugansk region, current insurgent supremo Igor Plotnitsky, a former Soviet army officer, was on some 63 percent with around a third of the ballots tallied, Russian media reported.

The run-up to the vote saw rebels carry out heavy shelling of government positions across the conflict zone. The UN says more than 4,000 people have died since fighting started in April.