Gunfire and blasts have been heard around an eastern city in Ukraine that has become the focus of an armed pro-Russian insurgency.

Ukraine’s police and security forces are “helpless” to quell unrest in two eastern regions bordering Russia, the country’s president has said.

Russia’s defence minister has announced new military exercises along the Ukrainian border just hours after Ukrainian troops killed at least two pro-Russia insurgents in eastern Ukraine.

Ukraine has taken its first military action against a pro-Russian uprising in the east as government forces repelled about 30 gunmen at an airport, beginning what the president called an “anti-terrorist operation” to restore authority in the region.

Army troops have restored control over a small airport in eastern Ukraine that had been occupied by pro-Russian militiamen, the acting president said.

Pro-Russian insurgents dug in across eastern Ukraine, fortifying their positions around seized buildings and erecting fresh barricades even as Ukrainian tanks took up positions outside one eastern city now controlled by armed men.

A Russian fighter jet made multiple close-range passes near an American warship in the Black Sea for more than 90 minutes on Saturday amid escalating tensions in the region, a US military official revealed today.

Ukraine’s acting president Oleksandr Turchynov has called for the deployment of United Nations peacekeeping troops in the east of the country, where pro-Russian insurgents have occupied buildings in nearly 10 cities.

Pro-Russian separatists have seized a police building in yet another city in Russian-leaning eastern Ukraine, defying government warnings that it was preparing to act against the insurgents.

Ukraine is launching a “large-scale anti-terrorist operation” to resist attacks by armed pro-Russian forces, President Oleksandr Turchynov said in a televised address yesterday.

The Crimean parliament has voted that the Black Sea peninsula will declare itself an independent state if its residents agree to split off from Ukraine and join Russia in a referendum.

Ukraine’s acting president has called for the formation of a national guard and for the mobilisation of reserves and volunteers into the country’s armed forces in order to counter Russian military aggression.

Ukraine will not give up “a single centimetre” of its territory, the country’s prime minister said.

“This is a declaration of war... We are on the brink of disaster,” Ukraine prime minister Arseny Yatsenyuk warned, as Russian troops surrounded at least two military bases in Crimea and the country’s Naval commander defected to Moscow.

A tense standoff was in place in the Crimea crisis tonight as Russian forces continued to surround a Ukrainian army base.

Barack Obama has warned Moscow “there will be costs” if Russia intervenes militarily in crisis-torn Ukraine.

Ukraine issued an arrest warrant yesterday for its ousted pro-Russian president over “mass murder” and appealed for $35bn (€25bn) in Western aid as Moscow denounced Kiev’s new reformist interim government as “Kalashnikov-toting people in black masks.”

Rescuers were continuing to search today for 34 miners trapped underground after a powerful explosion ripped through a coal mine in eastern Ukraine.

THIRTY-SEVEN miners were trapped after a gas explosion tore through a pit in Ukraine’s Donbass coalfield, destroying the main shaft and complicating rescue attempts.

President Viktor Yushchenko, introducing Ukraine’s new security chief, told the discredited State Security Service today that it should get out of politics and commerce and concentrate on fighting corruption and winning the people’s trust.