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.

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.

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

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.

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.

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.