Ukraine Accuses Russia of 'Aggression' amid East Unrest

Ukraine accused Moscow of "aggression" on Saturday after Kalashnikov-wielding gunmen seized two security building in its restive eastern rust belt amid spreading protests demanding the Russified region join Kremlin rule.

The coordinated attacks and a series of gunfights between militants and police in two eastern towns underscored the volatility of the crisis ahead of first direct talks between EU and U.S. diplomats and their Moscow and Kiev counterparts in Geneva on Thursday.

They also threaten to lead to further violence as far right forces who hold sway over the ex-Soviet state's western regions and who played a decisive role in this winter's anti-government protests watch the nation of 46 million veer toward a possible breakup.

Ukraine's foreign minister blamed the occupations on the "provocative activities of Russian special services" while a prominent nationalist called on militants in his Right Sector party -- branded as a neo-Nazi organisation by Moscow -- to "fully mobilize and prepare for decisive action".

And acting president Oleksandr Turchynov convened an emergency security meeting after his interior minster reported that a "gunfight" had erupted between local security forces and militants who had attacked a police station in the eastern town of Kramatorsk.

"The authorities of Ukraine view today's events as a display of aggression by the Russian Federation," Interior Minister Arsen Avakov wrote on his Facebook page.

Ukraine's interim government has been facing relentless pressure from Russia since its February ouster of an unpopular Kremlin-backed president and decision to seek closer ties with the West.

The seizures highlight how little sway Kiev's untested leaders have over pro-Russians who have since April 6 also controlled the Donetsk government seat and a state security building in the nearby eastern city of Lugansk.

Moscow has massed tens of thousands of troops on Ukraine's eastern border after annexing the Black Sea peninsula of Crimea and nearly doubled the rates it charges Kiev for gas.

Russia is now ready to demand prepayment from the cash-strapped government for future gas deliveries or halt supplies -- a move that would impact at least 18 EU countries and deepen the worst East-West standoff since the Cold War.

In a letter obtained by Agence France Presse and dated April 11, European Commission President Jose Manuel Barroso called for a common EU response to Russia's warnings over gas supplies.

A letter sent by Putin regarding energy supplies to some EU members "raises serious issues for Europe's collective energy security," Barroso wrote.

The issue would be raised at a meeting on Monday of EU foreign ministers and in a conference call with energy ministers, Barroso wrote, adding that the commission would facilitate a "joint approach for a reply" to Russia.

Saturday's unrest began with morning raids on a police station and regional security service center in Slavyansk -- a riverside town of 100,000 about 60 kilometers (35 miles) north of the regional capital Donetsk.

Ukraine's interior ministry said the first assault was led by 20 "armed men in camouflage fatigues" whose main purpose was to seize 20 machine guns and 400 Makarov guns stored in the police headquarters "and to distribute them to protesters".

An AFP reporter saw the Slavyansk police station surrounded by armed men in masks and camouflage who had set up a barricade of old tires and dumpsters in front of the police headquarters.

The interior ministry said some of the same gunmen had later occupied the city's state security service building.

"The protest participants are continuing to arm themselves with weapons seized from the police," the interior ministry said in a statement.

"The entire city... will defend the guys who seized this building," Slavyansk Mayor Neli Shlepa told Russia's Life News television outside the police headquarters.

Ukraine's interior minister said that a separate group of assailants had also unsuccessfully tried to seize the Donetsk prosecutor's office.

But an AFP reporter in the city saw about 200 pro-Russian protesters armed with clubs and sticks storm the police headquarters without meeting any resistance from anyone inside.

A few dozen anti-riot police who arrived at the scene were instead seen sporting orange and black ribbons symbolizing support for Russian rule -- a vivid sign of Kiev's slipping hold on Ukraine's eastern rust belt.

The Donetsk administration center is already being held by gunmen who have proclaimed the creation of their own "people's republic" and called on President Vladimir Putin to send Russian troops into eastern Ukraine.

Ukraine's embattled Prime Minister Arseniy Yatsenyuk promised during an unannounced visit to Donetsk on Friday to grant more powers to the country's regions and protect the east's right to use the Russian language.

But the Donetsk and Lugansk gunmen also want to stage independence referendums coinciding with snap presidential polls Ukraine will stage on May 25.

Both Western leaders and Kiev have accused the Kremlin of orchestrating the unrest in order to justify a possible future invasion of eastern Ukraine -- a charge Moscow flatly denies.

Kiev said Ukraine's interim Foreign Minister Andriy Deshchytsya told his Russian counterpart Sergei Lavrov by telephone on Saturday to "stop the provocative activities of Russian special services in the eastern regions of Ukraine."

But Moscow said Lavrov firmly rejected the accusation and "noted that similar claims... have been made by Washington, although we still have not been presented with any concrete proof."

Russia on Friday warned that it would boycott Thursday's Geneva talks should Ukraine try to regain control of the seized buildings through force.