A truce between Russia-backed separatists and the Ukrainian army will come into force on Monday in eastern Ukraine, according to Russia's foreign minister.

The deal was brokered on Saturday at the Munich security conference with the participation of Ukraine, Russia, Germany and France.

"It is positive that the contact group [of foreign ministers of the four countries] agreed once again for the start of a ceasefire on February 20," Sergey Lavrov said.

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The agreement also concerns "the start of the withdrawal of heavy arms" in eastern Ukraine.

The Munich meeting "examined where we were with the implementation of accords reached" by the presidents of the four countries in Berlin in October, Lavrov said.

"We observed that there hasn't been major progress in terms of results of the decisions taken in Berlin," he said.

Jean-Marc Ayrault, French foreign minister, said neither Russia nor Ukraine had offered any alternatives to the Minsk process.

"The meeting showed that Russians and Ukrainians had no other option but to respect Minsk. They have no alternatives," he said.

"We agree to meet quickly, perhaps in three weeks, to see if we can advance on the ceasefire, withdrawal of heavy weapons and exchange of prisoners. We need a lot of patience, because we can see a lack of will on either side."

Fighting has recently intensified in the conflict, killing nearly 30 people at the start of February.

Major development

The news of the deal overshadowed a major development announced in Russia.

President Vladimir Putin ordered Russian authorities on Saturday to temporarily recognise civil registration documents issued in separatist-held areas of eastern Ukraine, indirectly recognising the self-proclaimed republics of Donetsk and Luhansk.

The move will enable people from the conflict-hit region to travel, work or study in Russia.

The new legislation will be in place until a "political settlement of the situation" in these regions based on the Minsk peace accords, the Kremlin said.

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Ukrainian authorities sharply criticised Putin's decision, saying Russia had violated the Minsk peace process.

"For me, this is another proof of Russian occupation as well as Russian violation of international law," Ukraine's President Petro Poroshenko said in Munich.

Oleksander Turchynov, secretary of Ukraine's National Security and Defence Council, which is headed by Poroshenko, said: "This step completely negates the Minsk process."

Almost three years of fighting between government forces and Russia-backed rebels in eastern Ukraine have killed nearly 10,000 people.