Separatists Kill 7 Ukraine Troops as Pro-Moscow Rebel Survives 'Assassination Attempt'

Deadly violence flared in the restive east of Ukraine on Tuesday even as Europe stepped up its diplomatic efforts to resolve the escalating crisis on its doorstep.

German Foreign Minister Frank-Walter Steinmeier was in Ukraine to push the Kiev authorities and pro-Moscow rebels to come together at the negotiating table after the East-West security body OSCE drew up a roadmap aimed at easing tensions.

But the battle lines remained drawn, with Ukraine threatened with collapse following weekend independence referendums in the eastern industrial provinces of Donetsk and Lugansk.

Russia, despite expressing support for the "extremely important" roadmap, said the Kiev authorities must halt their military operation in the east if rebels are to comply with the peace initiative.

And Ukraine's interim Prime Minister Arseniy Yatsenyuk, in Brussels to seek EU support for his beleaguered government, fired back at Russia, accusing it of stealing his country's gas and threatening to take it to court over vital energy supplies.

On the ground, the Ukrainian military suffered one of its deadliest single days since the separatist insurrection in the east erupted in early April.

Kiev said seven soldiers were killed in an ambush by rebels armed with heavy weapons between the insurgent strongholds of Slavyansk and nearby Kramatorsk.

The defense ministry said a military convoy was attacked near a river in a village between Slavyansk and Kramatorsk by a group of about 30 men who fired heavy weapons including grenade launchers.

The troops responded, triggering "prolonged clashes" that left six soldiers dead and eight wounded, the ministry said.

A spokeswoman for the Ukrainian security services said later the death toll had risen to seven.

Another nine Ukrainian soldiers have been killed since Kiev launched a so-called "anti-terrorist" operation in the east in mid-April, a defense ministry official said.

It is not known how many police or other members of the security forces have been killed.

There had been fears that Russian President Vladimir Putin would move quickly to annex the territories as he did with Crimea in March, despite Western outrage.

While urging rebels to sign up to the OSCE roadmap, Moscow has also kept up the pressure on Kiev, insisting that negotiations on regional rights must take place before a presidential vote on May 25 and accusing the pro-Western interim government of refusing "real dialogue."

The crisis has plunged the West's relations with Russia to their lowest point since the Cold War and raised European concerns about the vital supply of Russian gas, much of which flows through Ukraine.

Yatsenyuk threatened to take Russia to the international arbitration court if it rejected proposals to settle their dispute over gas contracts and prices.

Meanwhile, after talks with Yatsenyuk in Kiev, Steinmeier said the situation in Ukraine remained "very threatening" but called for "a national dialogue."

"I hope this will create the conditions to take a step to bring back occupied territory, disarm armed groups step-by-step and reinstall the authority of the state," he said.

He also said the presidential election -- called by Kiev's new leaders after they took power in February -- will "play a crucial role" in bringing the country out of crisis.

Poland also sounded alarm bells, warning that its neighbor risked becoming a failed or divided state unless the EU effectively supports the May 25 vote.

In Moscow, the foreign ministry said it "expects" Ukraine rebels to comply with the OSCE roadmap, as long as Kiev does -- and called on Ukraine's leaders to agree to talks in the near future.

The Russian ministry also said Kiev had to immediately stop "reprisal raids" in the east -- using a term that refers to a Nazi massacre in 1943 -- and pull back troops from the encircled cities and towns.

The diplomatic flurry comes after eastern rebels Monday appealed to join Russia following what they claimed were resounding victories in independence referendums.

Both European and U.S. officials denounced the votes as illegal and Donetsk governor Serhiy Taruta said Tuesday the referendums were nothing more than a "social survey".

"As for the Donetsk People's Republic, such a republic does not exist legally or politically," he said. "There is only a dreamed-up name and nothing else."

Moscow however said it "respects" the votes and called for talks with rebels in the industrial regions of Donetsk and Lugansk, home to seven million of Ukraine's 46 million people.

Rebel officials in Donetsk said 89 percent of voters there backed breaking away from Ukraine in Sunday's referendum, while separatists in Lugansk said 94 percent had supported independence.

The Organization for Security and Cooperation in Europe, which began life as a forum for East-West dialogue in the Cold War, said Monday that Russian President Vladimir Putin is "supportive" of its roadmap for Ukraine.

The Vienna-based OSCE said the roadmap focuses on "restraint from violence, disarmament, national dialogue, and elections".

The OSCE has named veteran German diplomat Wolfgang Ischinger as a moderator for the talks.

Kiev is hosting a roundtable meeting on Wednesday involving the government, parliament and regional leaders but notably not any separatist representatives.

Kiev and Western leaders have accused Moscow of backing the rebels and on Monday EU foreign ministers announced new sanctions against Russians and Crimeans involved in the crisis.

Violence has flared for weeks in eastern Ukraine as government troops carry out operations against well-armed rebels who seized cities and towns in the chaos that followed the ouster of Ukraine's pro-Russian leader Viktor Yanukovych in February.

Ukrainian officials have said 49 people have died in the Donetsk region since the start of the unrest, and deadly clashes and an inferno in Odessa killed at least 42 people earlier this month.

Earlier on Tuesday, the rebels in Lugansk claimed their self-styled governor Valery Bolotov survived an "assassination attempt" after assailants opened fire on his car with automatic rifles, two days after the region held a referendum on self rule.

The rebel official was wounded when unidentified assailants shot at his car, a spokesman for the rebels told reporters.

"They shot with automatic weapons," the spokesman Vasily Nikitin said, adding that Bolotov was hospitalized.

"He lost a lot of blood but everything is fine now. His life is not in danger."

On Sunday, the Russian-speaking regions of Lugansk and Donetsk held self-rule referendums, with rebels claiming that an overwhelming majority chose to split from Ukraine.

Nikitin, the spokesman for the "Lugansk People's Republic", blamed central Kiev authorities for the shooting.

"We believe that the assassination attempt on Bolotov is Kiev's response to our referendum," he said.