Ukraine crackdown kills 20 pro-Russian rebels in pitched battle

In a fresh escalation of the virtual civil war in Ukraine, official forces fought a pitched battle with pro-Russian rebels on Friday and drove from police headquarters in the eastern city of Mariupol, killing 20 of them.

According to the Kiev interior ministry, the forces then withdrew from the centre of the city; and one Ukraine security officer was also killed in the clash, according to reports.

Interior Minister Arsen Avakov said an attempt by "terrorists" to seize police headquarters turned into a pitched battle with forces from the Ukrainian army, national guard, and security.

The action appeared to be one of the biggest yet in Kiev's attempt to end an insurgency in the country's east, though the number of dead could not be independently confirmed.

But reports said that having expelled the armed fighters from the yellow-stone building, burnt out in the course of the clashes, the Ukrainian forces and their armoured cars abandoned the area.

With presidential elections approaching in two weeks, Kiev is under international pressure to restore order across the country.

"A terrorist group of about 60 men armed with automatic weapons attacked the police headquarters ... About 20 terrorists were destroyed and four taken prisoner," Avakov said on his Facebook page.

"To those who come with weapons and who shoot and who take hostages, torture them, rob people, hiding behind various slogans - to them there can be only one answer from the Ukrainian state - annihilation."