Ukraine's embattled premier on Friday vowed to give more powers to the country's regions in an effort to stamp out a separatist insurgency as a new gas war with Russia threatened European supplies.

Prime Minister Arseniy Yatsenyuk's promise during an unannounced visit to the blue-collar coal mining region of Donetsk came as militants armed with Kalashnikovs barricaded themselves inside the local administration building and demanded a referendum on joining Russia.

A similar occupation of the state security office of the hardscrabble eastern city of Lugansk has confronted the leaders with their biggest challenge since their February ouster of a Kremlin-backed president and Russia's actions in Crimea.

Meanwhile, Ukraine said on Friday it would turn to Europe for gas and won a promise of help from Brussels after Russia warned it could cut supplies over Kiev's refusal to pay Moscow's "political, uneconomic price" for supplies.

Presenting a united front a day after Russian President Vladimir Putin wrote to the EU warning that its supplies could be disrupted if Ukraine failed to cover its bills, European officials said they had little to fear and would help Ukraine pay.

But Putin said on Friday Russia would fulfill its obligations to European gas clients and had no plans to halt deliveries to Ukraine.

Putin's gas threat prompted US President Barack Obama to raise the possibility of a third and most painful yet round of sanctions against Moscow.

Yatsenyuk flew overnight to Donetsk to enlist the help of its mayor and Rinat Akhmetov,  Ukraine's richest man and one of its most legendary powerbrokers, in finding a bloodless solution to the occupation of the local government seat.

Yatsenyuk immediately addressed one of the protesters' most pressing concerns by promising never to limit the use of the Russian language in the region.

"No one under any circumstances will restrict the use of a language that a person is accustomed to using," he said.

He also admitted he "must respond to people's desire to have more regional authority." "We will implement this task within the framework of constitutional reforms," said Yatsenyuk.

AFP - Reuters

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