Russian president Vladimir Putin has said Ukraine should withdraw its military from the eastern and southern regions of the country - a statement that could bolster anti-government insurgents who are seizing buildings.
Hours later, Ukraine's acting president ordered that the military draft be renewed, citing "threats of encroachment on the nation's territorial integrity" and interference by Russia in its internal affairs.
Moscow has consistently denounced Ukrainian security forces' largely ineffectual operation against the eastern insurgents and warned they should not commit violence against civilians.
In a telephone conversation with German chancellor Angela Merkel, Mr 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 favour 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 aged 18 to 25.
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.
In the regional capital city of Donetsk, anti-government demonstrators took over the regional prosecutor’s office today. Several dozen riot police standing guard at the office fired stun grenades and tear gas when some at the front of the crowd of several hundred people attempted to force their way into the building.
As the confrontation escalated, some in the crowd threw rocks and managed to wrest away shields from police. An Associated Press reporter saw a handful of officers being dragged away and beaten by members of the crowd.
Hundreds of onlookers accompanying the protesters shouted slogans and hurled abuse.
A car outside the building blared out patriotic second World War music. Inside, a passenger waved a flag bearing a doctored image of Soviet leader Josef Stalin in a black vest and holding a machine gun superimposed with the words: "Death to Fascism".
Upon occupying the building, protesters discarded the Ukrainian flag and replaced it with that of the Donetsk People’s Republic - a movement that seeks either greater autonomy from the central government, or independence and possible annexation by Russia.
Donetsk is the heartland of support for Russia-friendly former president Viktor Yanukovych, who was ousted in February after months of protests in the capital. Opponents of the government that succeeded him have seized buildings in about a dozen cities and towns in eastern Ukraine.
Local news website Novosti Donbassa reported that earlier in the day about 30 armed men arrived in six cars in the town of Amvrosiivka, which lies close to the Russian border, and took over the city council and forced the mayor to resign.
Yesterday, insurgents took control of the customs-service building in Donetsk and city hall in Alchevsk, an industrial centre of about 110,000 people, adding to the scores of buildings taken by the separatists over the past month in the east, where a dozen cities are now in the hands of the separatists.
There has also been a spate of reported kidnappings of pro-government politicians. The Svodoba nationalist party said a local party branch leader in Kostiantynivka, 40 miles north of Donetsk, initially managed to fight off attackers at his home but was taken away as he phoned for help.
Mr Turchynov has twice proclaimed “anti-terrorist” operations to regain control of the east, but to little effect.
Unlike many recent seizures of the government offices, the assault on the prosecutor’s office appeared to have been spearheaded by people armed with little more than sticks. However, at least one young man was seen with a handgun tucked into his trousers, and at least one firebomb was thrown at the building.
The armed element of the insurgency is focused on Slovyansk, a city 70 miles north of Donetsk in which seven European observers from the Organisation for Security and Cooperation in Europe remain held by pro-Russia gunmen.
Ms Merkel again called Mr Putin and asked for his assistance in freeing the group, her spokeswoman Christiane Wirtz said.
Russia denies allegations from Kiev and the West that it is influencing or fomenting strife in eastern Ukraine.
The Kremlin confirmed the conversation and said Mr Putin stressed “the main thing was for Ukraine to withdraw its troops from southeastern Ukraine, stop the violence and quickly start a broad national dialogue on constitutional reform”.
In Washington, the second-ranking official in Nato said the alliance now feels compelled to start treating Moscow as an adversary.
"In central Europe, clearly we have two different visions of what European security should be like," Alexander Vershbow, the deputy secretary-general of Nato, said in a question-and-answer session with reporters.
He said Russia’s annexation of Crimea and its apparent efforts to manipulate turmoil in eastern Ukraine have fundamentally changed the Nato-Russia relationship.
Press Association