Germany has welcomed a Russian offer to help efforts to free a group of European military observers in eastern Ukraine where they are being held by pro-Russian forces.<br /><br />Russia’s Foreign Minister Sergei Lavrov has spoken by phone on Saturday to Swiss President Didier Burkhalter, acting president of the Organisation for Security and Cooperation in Europe (OSCE).<br /><br />A separatist leader in Slovyansk has offered to exchange the eight German-led monitors for fellow rebels being held by the Kyiv authorities. The de facto mayor of the town, Vyacheslav Ponomaryov, said the captives were being kept in good conditions.<br /><br />“One of the soldiers suffers from diabetes, but it is not a serious condition, he is on tablets. There is medicine there is food,” said Ponomaryov.<br /><br />He said the Russian government had not been in contact with him to discuss the observers’ release.<br /><br />“They are not observers, they are spies. We have information confirming that. The information confirming their spying activities was in their papers,” said separatists’ representative Yevgeny Gorbik, echoing earlier claims. <br /><br />Moscow has said what it calls “public structures” controlling parts of southeastern Ukraine had not been properly informed of the observers’ plans to travel there.<br /><br />An OSCE negotiating team is said to be on its way to the region to try to secure the captives’ release.<br /><br />Ukraine’s acting prime minister – who met Pope Francis in the Vatican on Saturday – has claimed that Russian military planes violated Ukrainian airspace.<br /><br />Arseniy Yatsenyuk’s comments came after a visit to a church popular with his country’s Catholics, where he lit a candle for those killed in Ukraine’s unrest. <br /><br />Kyiv has rejected Russian demands that it stop its military operations in the southeast to defuse the crisis.<br /><br />EU diplomats are to meet on Monday to discuss further sanctions against Russia.