Moscow, Sha'ban 2, 1435, May 31, 2014, SPA -- An observer mission from the Organization for Security and Co-operation in Europe (OSCE) should remain in Ukraine despite security concerns, dpa cited the Russian Foreign Ministry as saying on Saturday. The news comes after Wolfgang Ischinger, the OSCE's mediator in Ukraine national unity talks, suggested earlier this week that the organization might have to withdraw the mission if its employees' lives remain in danger. In a statement carried by the Russian Itar-Tass news agency, the ministry suggests that in the light of Kiev's military crackdown on pro-Russian separatists in restive eastern regions, the work of international observers is "essentially important." A group of OSCE monitors remained in detention on Saturday, with separatist leader Vladimir Rogov confirming that the four men were suspected of espionage. "We are in constant contact with the OSCE mission. They know that their boys are okay," Rogov told reporters in the eastern city of Donetsk. Another separatist spokesman suggested that the men's release could be negotiated in exchange for the release of pro-Russian separatists detained by the government in Kiev. Russia said its mediators were in negotiations with rebel groups on behalf of the detained men. "The release is being delayed," said Andrei Kelin, Russian ambassador to the OSCE. -- SPA 18:05 LOCAL TIME 15:05 GMT www.spa.gov.sa/1238543