German Foreign Minister Frank-Walter Steinmeier told reporters before leaving a meeting of top European Union diplomats in Brussels on Monday that this week could be "decisive" for the future of Ukraine.

Steinmeier was to meet with newly elected Ukrainian President Petro Poroshenko and other top Ukrainian officials in Kyiv later on Tuesday.

Cease-fire observed

His visit was to come just hours after a major pro-Russian separatist group fighting government forces in eastern Ukraine announced that they would comply with a cease-fire declared by President Poroshenko on Friday.

The military force of the "Donetsk People's Republic is bound to end fighting in response to the cease-fire," Alexander Borodai, the appointed prime minister of the region's separatists, who have declared themselves independent from Ukraine, was quoted as saying by Russia's Interfax news agency on Monday.

The announcement came after the separatists had ignored the cease-fire declaration over the weekend. The breakthrough came after a meeting in Donetsk mediated by Swiss diplomat Heidi Tagliavini on behalf of the Organization for Security and Co-operation in Europe (OSCE) and involving Russia's ambassador to Ukraine, Mikhail Zurabov, and former Ukrainian President Leonid Kuchma.

It wasn't immediately clear whether separatists in other regions would comply with the truce.

EU foreign ministers meeting

European Union foreign ministers meeting in Brussels on Monday urged Russian President Vladimir Putin to support the peace plan presented by Poroshenko last Friday.

"This week must be dedicated to bringing about a de-escalation of the conflict. That is the priority," French Foreign Minister Laurent Fabius said following the talks. "We have called on Russia to get on board and that has to happen in the next few days," Fabius said, adding there "were contradictory signs" of Moscow's intentions.

Russian President Putin has said that while he supports an end to the fighting, the peace plan presented by Poroshenko was not viable.

pfd/kms (AFP, dpa, AP)