Russian President Vladimir Putin has taken a tentative step toward defusing the tense situation in eastern Ukraine.

Russian President Vladimir Putin has taken a tentative step toward defusing the tense situation in eastern Ukraine. Photo: Reuters

Moscow: President Vladimir Putin asked Russia's upper house on Tuesday to revoke the right it had granted him to order a military intervention in Ukraine in defence of Russian-speakers there.

Minutes before he spoke, Kiev said pro-Russian rebels in east Ukraine had shot down a military helicopter, most likely killing all nine on board. It was the most serious breach of a temporary ceasefire agreed in talks between government and rebels less than 24 hours earlier.

Mr Putin's move received a cautious welcome in the West as a sign Moscow was ready to help engineer a settlement in Ukraine's largely Russian-speaking east, where a pro-Russian uprising against Kiev began in April.

Ukrainian President Petro Poroshenko called it a "first practical step" following Mr Putin's statement of support last weekend for Mr Poroshenko's peace plan for eastern Ukraine.

But later he told security chiefs to "open fire without hesitation" if government forces came under attack, and "did not rule out bringing the ceasefire regime to an early end" if rebels continued to breach it, his press service said.

Mr Putin himself said he now expected Ukraine to begin talks on guaranteeing the rights of its Russian-speaking minority, which Russia would continue to defend.

"It is not enough to announce a ceasefire," he told reporters on a visit to Vienna. "A substantive discussion of the essence of the problems is essential."

In the March 1 resolution, the Federation Council had granted Mr Putin the right to "use the Russian Federation's Armed Forces on the territory of Ukraine until the social and political situation in that country normalises".

That resolution, together with Russia's March annexation of Crimea from Ukraine, helped push East-West relations to their lowest ebb since the Cold War and led the United States and Europe to impose sanctions on Moscow.

The Federation Council was due to discuss the reversal requested by Mr Putin on Wednesday and expected to approve it.

NATO spokeswoman Oana Lungescu said: "We expect Russia to withdraw its troops and military infrastructure from the Ukrainian border, end its support for armed separatist groups, and the flow of weapons and mercenaries across its border, as well as denounce publicly separatist violence in Ukraine."

A spokeswoman for EU foreign policy chief Catherine Ashton declined to comment when asked whether Mr Putin's step would reduce the likelihood of tougher sanctions being agreed at an EU summit in Brussels on Friday.

The White House welcomed Mr Putin's backing for the ceasefire, but said there must be "tangible actions" to defuse the crisis.

There was no word on the progress of peace talks, at which Russia and the Organisation for Security and Co-operation in Europe are represented alongside rebel leaders and Kiev's representative, former president Leonid Kuchma.

But it was clear that the ceasefire, due to expire on Friday morning, was under heavy strain.

The Ukrainian helicopter downed near the rebel stronghold of Slaviansk was carrying technicians who were installing equipment to monitor violations of the peace plan, the government said.

Igor Strelkov, the top rebel commander in Slaviansk, was quoted on a rebel Facebook page as saying: "Talks with them [the Kiev government] are possible only from a position of strength."

Elsewhere, a witness said rebels had opened fire on two Ukrainian armoured personnel carriers leaving Donetsk airport, which is under government control. Kiev said three servicemen were killed in rebel attacks on military posts and checkpoints. But rebels accused government forces of firing first.

Mr Putin himself appeared to cast doubt on a central element of Mr Poroshenko's plan: that rebels should lay down their weapons.

He said it was "pointless" to demand this when far-right militants who had helped to topple Moscow-backed president Viktor Yanukovich in February had not been disarmed by Kiev.

Russia itself has already pulled back tens of thousands of troops it had moved close to the border earlier in the crisis.

Those troops had also provided an unspoken threat to support the well-equipped but sometimes disunited rebels in eastern Ukraine against government forces trying to wrest back the towns and administration buildings they had seized.

Like many of eastern Ukraine's Russian speakers, Moscow was infuriated by the fall of Mr Yanukovich after he pulled out of an association agreement with the EU in favour of closer relations with Moscow, Kiev's former master within the old Soviet Union.

Reuters