Pro-Russian separatists in eastern Ukraine said on Tuesday they were holding an American journalist in the city of Slaviansk and the online news site Vice News said it was trying to secure the safety of its reporter, Simon Ostrovsky.Journalists working in the area said Ostrovsky had been detained by gunmen on Monday and, unlike others taken with him, had not yet been released.The local separatist leader Vyacheslav Ponomarev told reporters on Tuesday that Ostrovsky is now working for pro-Russian, secessionist militia in Sloviansk, the Russian news site gazeta.ru reported.“Nobody abducted [him], nobody holds [him] hostage, he is now with us,” Ponomarev was quoted as saying at a news conference that was held amid reports that Ostrovsky had been kidnapped. Ponomarev added that Ostrovsky was now “working, preparing materials.”Ponomarev said Ostrovsky holds Israeli and American passports. Vice News said on its Web site it was "aware of the situation and is in contact with the US State Department and other appropriate government authorities to secure the safety and security of our friend and colleague, Simon Ostrovsky".He noted that during the news conference a woman working with the separatists "called us all liars" and then asked journalists for donations for the funerals of militants who had been killed in a gunfight the previous day.The US State Department on Tuesday condemned the detention of journalists by pro-Russian separatists in eastern Ukraine, following reports that an American journalist was being held in Slaviansk."Obviously there has unfortunately been a range of journalists who have been detained or held hostage over the last couple of days. We, of course, condemn the taking of hostages," US State Department spokeswoman Jen Psaki said when asked about the detention of Vice News journalist Simon Ostrovsky.Ostrovsky has been covering the crisis in Ukraine for weeks. His last posting on Twitter was on Monday when he covered an earlier news conference by the separatist leader.“Sloviansk pro-Russia ‘mayor’ threatens to throw journalist out for ‘provocative’ question about former mayor being held under guard,” Ostrovsky wrote Monday. His following message — his last before Ponomarev’s announcement about Ostrovsky — was: “Now he’s not letting reporters leave the press conference: ‘you’ll go as you came in. In a group.’ That’s one way to guarantee coverage.”Ukraine has seen violent clashes between pro-Russian protesters and other groups since the ousting in February of the government of former president Viktor Yanukovych in a revolution which erupted over his perceived pro-Russian policies. Ukraine’s interim government has announced new elections scheduled for next month.On Monday, pro-Russian separatists said their newly-launched television station in Sloviansk would deal “a powerful blow to the biblical matrix and zombie Zionists,” the Ukrainian news site tvplus.dn.ua reported Monday.Since the revolution erupted in November, Ukraine, which has relatively low levels of anti-Semitic violence, has seen several serious attacks including a stabbing and the attempted torching of two synagogues, most recently last week in Nikolayev.The Ukrainian government and Russian government officials, as well as their supporters in Ukraine, have exchanged allegations of anti-Semitism.