Poroshenko made a new push to end the conflict in Ukraine's eastern regions on Monday, telling a news conference he would join Russian President Vladimir Putin, German Chancellor Angela Merkel and French President Francois Hollande for talks on January 15, in the Kazakh capital Astana.

The Ukrainian president said he wanted eastern Ukraine, and Crimea, annexed by Russia in March, back under the control of Kyiv.

"The most important thing is to turn a fragile ceasefire into a stable peace and return previously occupied territories under the control of Ukrainian authorities," he said.

The conflict in eastern Ukraine has killed more than 4,600 people since April. But Poroshenko said Kyiv lacked the resources to regain full control by military means.

"We haven't got the resources for an offensive today," he said.

His comments come after the breakdown of the first talks in three months between Kyiv and pro-Russian separatists, last week in Minsk. However, the talks did produce a prisoner swap between both sides.

The meeting was meant to secure a shaky ceasefire agreed in Minsk back in September, as well as a withdrawal of heavy weapons by both Ukrainian government forces and the separatists. But it appeared both sides were reluctant to give any ground.

"Ukraine will never - and we are supported in this by the entire world - allow the (original September) Minsk agreements to be altered," Poroshenko said on Monday.

Poroshenko also said three Ukrainian soldiers had been killed during a battle at the disputed airport near rebel-held Donetsk.

Ukraine and the West have accused Moscow of stoking the fires of conflict in eastern Ukraine by supplying the separatists with troops and weapons, something the Kremlin has denied.

Meanwhile, Russia is experiencing deep economic troubles caused by lower oil prices and Western economic sanctions imposed over the Ukraine conflict.

On Monday, it was announced that Russian growth declined for the first time since 2009 - with gross domestic product (GDP) falling by 0.5 percent in November, compared to the same month last year.

The ruble fell to $57 on the news on Monday morning. The Russian currency, which is one of the worst performing currencies of 2014, had started losing ground against the greenback again on Friday, following a five-day rally.

jr/ksb (Reuters, dpa, AFP)