Watch: Clashes break out near Independence Square in Kiev
Protesters demanding more power for Ukraine's regions stormed government buildings in Luhansk yesterday, seizing control of key sites in one of the largest cities in Ukraine's troubled east.
The move further raises tensions in the east, where insurgents have seized city halls, police stations and other government buildings in at least 10 cities and towns.
The unrest was stoked by geopolitical tensions as Moscow yesterday accused Washington of bringing back "Iron Curtain" policies in the fierce showdown over Ukraine, while the West revealed its new sanctions included measures against Russia's military chief.
The demonstrators who overran the buildings were seeking - at the very least - a referendum on granting greater authority to Ukraine's regions. Eastern Ukraine, which has a large Russian-speaking population, was the heartland of support for Viktor Yanukovych, the president who fled to Russia in February. The government that replaced him in Kiev has resisted those demands so far, fearing they could lead to a breakup of the country or mean that more regions - like Crimea - are annexed by Russia.
The unrest began when around 1,000 demonstrators gathered in front the headquarters of the government of Luhansk region. About 150 people, some masked and wielding baseball bats, broke out of the crowd and charged into the building, meeting no resistance.
Separatists then seized the prosecutor's office and television centre before opening fire with automatic weapons at the local police headquarters. Around 20 gunmen shot at the building, trying to force police to surrender their weapons.
Luhansk, a city of about 450,000, is just 25 kilometres west of the border with Russia.
Russia has massed tens of thousands of troops in areas near the Ukrainian border, feeding concerns that Moscow aims to use unrest in the east as a pretext for an invasion.
In Kiev, Deputy Foreign Minister Danylo Lubkivsky again accused Russia of fomenting the unrest in Ukraine and said the insurgents it was supporting were violating an international agreement on overcoming the crisis.
"The east, though, still remains a trouble spot, with civilians being threatened and attacked. Russian terrorists are refusing to surrender arms," he said.
The heightened tensions on the ground were matched by an escalation in language from Russia, which underlined the cold war echoes of the crisis.
Russian Deputy Foreign Minister Sergei Ryabkov tore into the United States for leading the sanctions charge on Monday, especially for its decision to curb hi-tech exports to Russia that could have military uses. "All of that is a blow to our high-tech enterprises and industries," Ryabkov told online newspaper Gazeta.ru 
"This is a revival of a system created in 1949 when Western countries essentially lowered an 'Iron Curtain', cutting off supplies of high-tech goods to the USSR and other countries."
The European Union revealed that General Valery Gerasimov, chief of the general staff of Russia's armed forces and the country's deputy defence minister, was one of 15 Russians and Ukrainians targeted by an asset freeze and travel ban in the bloc's latest blacklist.
Russia's foreign ministry responded by saying the European bloc was "doing Washington's bidding".
The White House on Monday slapped sanctions on seven Russian officials and 17 companies close to Russian President Vladimir Putin, while Canada added nine names and two banks, and Japan said it was denying visas to 23 Russians. The Kremlin has vowed "painful" retaliation against Washington for the measures.
Reuters, Agence France-Presse