An armed man in military fatigues stands guard outside a regional administration building seized by separatists in the eastern Ukrainian city of Slavyansk on Wednesday. Photo: AFP

 Russia issued a blunt warning Wednesday it would respond if its interests are attacked in Ukraine, as pro-Kremlin rebels in the restive east of the country braced for a new military offensive by Kiev.

The warning by Russian Foreign Minister Sergei Lavrov, recalling the 2008 war with Georgia over breakaway South Ossetia, came as US troops were headed to the region in a show of force after Washington again warned Moscow of new sanctions over the escalating crisis.

"If we are attacked, we would certainly respond," Lavrov told state-controlled RT television.

"If our interests, our legitimate interests, the interests of Russians have been attacked directly, like they were in South Ossetia for example, I do not see any other way but to respond in accordance with international law."

He did not elaborate, but the reference to South Ossetia strongly hinted at the possibility of military action.

The United States, meanwhile, said it plans to deploy 600 troops to Poland and the Baltic states starting Wednesday to "reassure our allies and partners."

Ukraine's Acting President Oleksandr Turchynov late Tuesday ordered a new "anti-terrorist" operation against separatists holding a string of eastern towns after the discovery of two "brutally tortured" bodies.

One of the dead was a local politician from Turchynov's party who was kidnapped nearly a week ago, the leader said, blaming his death on the rebels.

Kiev's offensive threatens to sound the death knell for an already tattered agreement struck last week in Geneva between Ukraine, Russia and the West to ease the crisis, which some fear could tip into civil war.

"Security agencies are working to liquidate all the groups currently operating in Kramatorsk, Slavyansk and the other towns in the Donetsk and Lugansk regions," said Deputy Prime Minister Vitaly Yarema, according to the Interfax Ukraine news agency.

Pro-Moscow insurgents in Slavyansk - an eastern Ukrainian town which has become a tense flash point in recent days - are holding two journalists, an American working for Vice News, Simon Ostrovsky, and a Ukrainian working for a pro-Kiev outlet, Irma Krat.

Slavyansk's local rebel leader Vyatcheslav Ponomarev told reporters that the American "is not being detained, was not abducted, has not been arrested" and claimed he was "working" in one of the rebel-occupied buildings.

The US State Department said it was "deeply concerned" Wednesday over reports that an American journalist was kidnapped by pro-Russian separatists in Ukraine.

"We condemn any such actions, and all recent hostage takings in eastern Ukraine, which directly violate commitments made in the Geneva joint statement," Psaki said.

"We call on Russia to use its influence with these groups to secure the immediate and safe release of all hostages in eastern Ukraine," she said.

AFP

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