The German government said Russian President Vladimir Putin on Sunday accepted a proposal by Chancellor Angela Merkel to set up a "contact group" aimed at facilitating dialogue in the Ukraine crisis.

Merkel raised the idea in a phone conversation in which she accused Putin of breaking international law with the "unacceptable Russian intervention in Crimea." German government spokesman Georg Streiter said in a statement that Putin also accepted the idea of setting up a fact-finding mission.

A Kremlin statement said Putin defended Russia's action against "ultranationalist forces" in Ukraine and insisted measures taken so far were "fully adequate." It said Putin directed Merkel's attention to the "unrelenting threat of violence" to Russian citizens and the Russian-speaking population.

It didn't refer specifically to Merkel's proposal but mentioned a need to continue "consultations in both a bilateral ... and multilateral format with the aim of cooperating to normalize the socio-political station in Ukraine."

Earlier Sunday, German Foreign Minister Frank-Walter Steinmeier said the Organization for Security and Cooperation in Europe could be asked to put together a fact-finding mission to determine what is really happening in Crimea and eastern Ukraine.

He added that an international "contact group" - involving European countries and perhaps the United Nations along with Russia and Ukraine - could be part of the solution. Streiter said the group could be led by the OSCE - a body that includes 57 countries, among them European Union nations, Russia, Ukraine and the United States.

"In the end, the result must be that Russian soldiers return to their barracks," Steinmeier told ARD television.

On Monday, EU foreign ministers will meet to discuss the crisis.

Steinmeier stressed dialogue rather than possible action against Russia, and said there are differences among leaders of the Group of Eight industrial nations over Moscow's future in the club.

"Some say we must now send a strong signal and exclude Russia," he added. "Others say - I am more with them - that the G-8 format is actually the only format in which we from the West still speak immediately with Russia, and should we really sacrifice this one format?"

"I think we have to see that we contribute to de-escalation in Ukraine," Steinmeier said.