The self-styled mayor of Slaviansk Ponomaryov attends a news conference in the mayor's office in Slaviansk
The self-styled mayor of Slaviansk Vyacheslav Ponomaryov attends a news conference in the mayor's office in Slaviansk April 26, 2014. Separatists in the eastern Ukrainian city of Slaviansk are ready to exchange a group of international observers they are holding for fellow rebels who are in the custody of the Ukrainian authorities, Ponomaryov said on Saturday. REUTERS/Gleb Garanich (UKRAINE - Tags: POLITICS CIVIL UNREST HEADSHOT)
The self-styled mayor of Slaviansk Ponomaryov attends a news conference in the mayor's office in Slaviansk
The self-styled mayor of Slaviansk Vyacheslav Ponomaryov attends a news conference in the mayor's office in Slaviansk April 26, 2014. Separatists in the eastern Ukrainian city of Slaviansk are ready to exchange a group of international observers they are holding for fellow rebels who are in the custody of the Ukrainian authorities, Ponomaryov said on Saturday. REUTERS/Gleb Garanich (UKRAINE - Tags: POLITICS CIVIL UNREST)
Journalists and security guard attend a news conference of self-styled mayor Vyacheslav Ponomaryov in the mayor's office in Slaviansk
Journalists and a security guard attend a news conference of self-styled mayor Vyacheslav Ponomaryov in the mayor's office in Slaviansk, April 26, 2014. Separatists in the eastern Ukrainian city of Slaviansk are ready to exchange a group of international observers they are holding for fellow rebels who are in the custody of the Ukrainian authorities, their leader said on Saturday. REUTERS/Gleb Garanich (UKRAINE - Tags: POLITICS CIVIL UNREST MILITARY CRIME LAW)
The self-styled mayor of Slaviansk Ponomaryov attends a news conference in the mayor's office in Slaviansk
The self-styled mayor of Slaviansk Vyacheslav Ponomaryov attends a news conference in the mayor's office in Slaviansk April 26, 2014. Separatists in the eastern Ukrainian city of Slaviansk are ready to exchange a group of international observers they are holding for fellow rebels who are in the custody of the Ukrainian authorities, Ponomaryov said on Saturday. REUTERS/Gleb Garanich (UKRAINE - Tags: POLITICS CIVIL UNREST HEADSHOT)
Russia's Lavrov tells Kerry U.S. should press Kiev to rein in army
UKRAINE-CRISIS/LAVROV-KERRY (URGENT):Russia's Lavrov tells Kerry U.S. should press Kiev to rein in army
Russia offered support in effort to free OSCE monitors - Germany
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Pro-Russian supporters rally outside the Mariupol town hall in east Ukraine
Pro-Russian supporters rally outside the Mariupol town hall in east Ukraine April 26, 2014. Russia will take all possible steps to free detained OSCE military observers in the Ukrainian town of Slaviansk, Russian news agencies reported on Saturday, citing Russia's envoy to the Vienna-based Organisation for Security and Co-operation in Europe. REUTERS/Baz Ratner (UKRAINE - Tags: POLITICS CIVIL UNREST)
A man reads the Bible next to an altar inside the Mariupol town hall in east Ukraine
A man reads the Bible next to an altar inside the Mariupol town hall in east Ukraine April 26, 2014. Russia will take all possible steps to free detained OSCE military observers in the Ukrainian town of Slaviansk, Russian news agencies reported on Saturday, citing Russia's envoy to the Vienna-based Organisation for Security and Co-operation in Europe. REUTERS/Baz Ratner(UKRAINE - Tags: POLITICS CIVIL UNREST)
A pro-Russian masked man walks past a broken window inside the Mariupol town hall in east Ukraine
A pro-Russian masked man walks past a broken window inside the Mariupol town hall in east Ukraine April 26, 2014. Russia will take all possible steps to free detained OSCE military observers in the Ukrainian town of Slaviansk, Russian news agencies reported on Saturday, citing Russia's envoy to the Vienna-based Organisation for Security and Co-operation in Europe. REUTERS/Baz Ratner (UKRAINE - Tags: POLITICS CIVIL UNREST TPX IMAGES OF THE DAY)