The United States, the European Union, Russia and Ukraine will meet next week to discuss the Ukraine crisis, offering a glimpse of possible diplomatic progress in the conflict.
The meeting will involve US Secretary of State John Kerry, EU foreign policy chief Catherine Ashton, Russian Foreign Minister Sergei Lavrov and Ukraine's Foreign Minister Andriy Deshchytsia, the EU said on Tuesday.
A spokesman for Ashton said the talks were aimed at "de-escalating" the crisis in Ukraine.
Further details of the meeting, which will be held at an unspecified location in Europe, are still being worked on, an EU source said.
Separately, an EU diplomat said the EU plans to set up a special support group to help Ukraine stabilise its precarious economy and political situation.
In a phone call on Monday, Kerry and Lavrov had discussed convening direct talks in the next 10 days between Ukraine, Russia, the US and the EU to defuse tensions, the US State Department said.
The EU's confirmation of the meeting came soon after Kerry accused Russian agents and special forces of stirring separatist unrest in eastern Ukraine, saying Moscow could be trying to prepare for military action as it had in Crimea.
Kerry and Lavrov held talks in Paris on March 30 about ways to defuse the crisis over Ukraine, with Kerry telling Moscow then that progress depended on a Russian troop pullback from Ukraine's borders.
Meanwhile, more than 50 people left a state security service building overnight that had been seized by pro-Russia activists in eastern Ukraine, following negotiations between protesters and officials, according to Ukraine's state security service (SBU).
The SBU said on Tuesday that the protesters who seized the local headquarters of state security in Luhansk on Sunday had wired it with explosives and were holding 60 people hostage, though this was denied by the protesters themselves.
After negotiations overnight, 51 people left the building without weapons, the SBU in the Ukrainian capital Kiev said. It was unclear if they were protesters or hostages.
Interfax Ukraine news agency later put this number at 56 and said negotiations were continuing between the protesters and local officials to end the occupation.
The activists denied on Tuesday they had any explosives or were holding hostages but admitted they had seized an armoury full of automatic rifles.
The Luhansk building was one of several seized by protesters in the east of the country demanding regional referendums on independence from Kiev.
Protesters in Donetsk, to the south, remain in control of the main regional authority building, but authorities ended the occupation in the city of Kharkiv.
The Ukrainian government says the occupations are part of a Russian-led plan to separate the country.