Members of the Ukrainian security services stand near a armoured personnel carrier at a checkpoint near the town of Slaviansk, east Ukraine May 1, 2014. [Photo/Agencies]

Ukraine crisis

SLOVYANSK, Ukraine - Gunfire and blasts were heard early Friday around an eastern city in Ukraine that has become the focus of an armed pro-Russian insurgency, whose leaders claimed that government troops had assayed a military assault in an attempt to retake control.

Vyacheslav Ponomarev, the mayor of Slovyansk, said self-defense forces had shot down two helicopters and taken one pilot hostage. He said no Ukrainian troops could be seen in the city.

The official spokesman for the military wing of the pro-Russian forces, who would give only his first name, Vladislav, said fighting had broken out at several points around the city. He said government armored vehicles were seen on roads leading into Slovyansk and claimed that Ukrainian troops had made incursions into the city itself.

Details of these claims could not be independently confirmed.

An Associated Press cameraman saw black plumes of smoke on the edge of the city. An emergency siren had sounded at dawn.

If the Ukrainian military action is confirmed, it would be the first major assault against the insurgents, who have seized police stations and other government buildings in about a dozen cities in southeastern Ukraine.

The armed element of the insurgency is focused on Slovyansk, a city 160 kilometers (100 miles) west of Russia in which seven European military observers from the Organization for Security and Cooperation in Europe remain held by pro-Russia gunmen.

Russian President Vladimir Putin said Thursday that Ukraine should withdraw its military from the eastern and southern regions of the country.

In a telephone conversation with German Chancellor Angela Merkel, Putin said the removal of military units was the "main thing,'' but it was unclear if that could be construed as an outright demand.

Oleksandr Turchynov's conscription order marked a turnaround for the country, which last year announced plans to end military conscription in favor of an all-volunteer force. His order did not specify where conscript-bolstered forces could be deployed. The renewal of military conscription affects only men 18 to 25 years old.

Earlier in the week, the acting president said police and security forces had been effectively "helpless'' against insurgents in the Donetsk and Luhansk regions, the heart of the unrest, and that efforts should be focused on preventing the instability from spreading to other parts of the country.