German Chancellor Angela Merkel said in a statement on Saturday that she was willing to attend a summit with the heads of state of France, Russia and Ukraine, but that the summit could only take place if there were concrete advances on the Ukraine crisis.

Ukrainian President Petro Poroshenko has invited the leaders for talks in Kazakhstan on January 15 to discuss solutions to the crisis in his country's east.

Merkel's spokesman Steffen Seibert said the chancellor spoke to Russian President Vladimir Putin earlier on Saturday, demanding that all sides needed to contribute toward "speedy progress on the basis of the Minsk agreement."

Russia needed to assert itself on separatists in eastern Ukraine, the chancellor added, saying that if "something like this kept happening," it could pose a danger to peaceful coexistence.

Minsk pact not yet successful

Earlier Saturday, Poroshenko accused Moscow of heating up the conflict on his country's eastern border, demanding that the clauses of the Minsk agreement be implemented immediately.

The "only way" towards de-escalation was the implementation of the agreement, Poroshenko emphasized during a meeting with Latvia's Foreign Minister Edgars Rinkevics. Latvia, which currently heads the EU's rotating presidency, said that it supported "Ukraine's territorial integrity" and did not recognize Russia's annexation of Crimea.

The Minsk pact, signed in September, called for a ceasefire and that all "illegally armed groups" leave Ukrainian territory. According to Kyiv, 7,500 Russian soldiers are currently active in eastern Ukraine and two of its soldiers had died in a recent ceasefire violation.

Meanwhile, Russia has exerted more pressure on Kyiv, demanding that the country repay a Russian credit of $3 billion (2.5 billion euros) earlier than scheduled. Kyiv had violated terms of the credit, Russia's Finance Ministry stated, adding that Ukraine was supposed to keep its domestic debt under 60 percent of the gross national product and repay the debt within one year.

Fighting in eastern Ukraine, sparked by the annexation of the Crimean Peninsula last March and Russia's alleged support of anti-Kyiv rebels, has resulted in more than 4,700 deaths.

mg/cmk (Reuters, AFP)