Ukrainian leader vows to punish pro-Russia rebels

A pro-Russian fighter holds a club at a regional state building in the eastern Ukrainian city of Donetsk on Thursday. Viktor Drachev / Agence France-Presse

Militants shot down Mi-8 helicopter with surface-to-air missile, killing 12

Ukraine's president-elect Petro Poroshenko vowed to punish pro-Russian rebels who downed an army helicopter in the east of the country, killing 12 troops in one of the deadliest attacks of the insurgency.

The militants shot the Mi-8 helicopter gunship out of the sky with a sophisticated surface-to-air missile on Thursday, prompting the White House to say the incident raised concerns about the rebels being supplied "from the outside".

"We have to do everything we can to ensure no more Ukrainians die at the hands of terrorists and bandits. These criminal acts by the enemies of the Ukrainian people will not go unpunished," said Poroshenko, according to Ukrainian news agencies.

One of the separatists' leaders made a surprise admission on Thursday that 33 out of more than 40 rebels killed in a raid on Donetsk airport this week were Russian nationals from Muslim regions such as Chechnya.

The revelation challenged President Vladimir Putin's rejection of Russian links to the separatist drive and supports Kiev's claims that the rebels do not represent the true will of the miners and steel workers who have turned the east into the economic engine of Ukraine.

US Secretary of State John Kerry said late on Thursday there was "evidence of Russians crossing over, trained personnel from Chechnya trained in Russia, who've come across to stir things up, to engage in fighting".

Kerry urged Russia to take advantage of Sunday's presidential election and "build a road forward where Ukraine becomes a bridge between the West and the East".

Russian troops massed on Ukraine's borders are also moving back toward Moscow, but there are still "danger signs", he told PBS television.

Moscow, meanwhile, called on Kiev to impose an immediate ceasefire and urged the West to use its influence to prevent "a national disaster" in Ukraine.

"The international community awaits an immediate ceasing of military activities from Kiev in the east of the country and the withdrawal of troops. Without that, achieving peace in Ukraine is impossible," the foreign ministry said.

Western-backed Poroshenko - winner of 54.7 percent of Sunday's vote and due to be inaugurated on June 7 - needs to avert another showdown with Russia that could see his economically teetering nation cut off from gas supplies by the start of next week.

But cash-strapped Ukraine appeared to avert the immediate threat of a gas cut-off when the European Union announced that a new round of talks between the EU, Russia and Ukraine will be held in Berlin on Friday.

EU Energy Commissioner Guenther Oettinger, who will attend the meeting, said earlier this week that Russia and Ukraine had a "good chance" of striking a deal by Sunday.

Yet the Kiev government's attention on Thursday was fixed on Slaviansk - an industrial city of 120,000 mostly ethnic Russians that was the first of a dozen towns and cities seized by the rebels in response to the February ouster in Kiev of a pro-Kremlin president.

Agence France-Presse