Russian President Vladimir Putin has accepted a proposal by German Chancellor Angela Merkel aimed at easing tensions in Ukraine, the German government has said.

The German proposal involves a fact-finding mission and a “contact group” on Ukraine that could be led by the Organisation for Security and Cooperation in Europe.

Government spokesman Georg Streiter said the proposal came during the telephone conversation in which Mrs Merkel accused Mr Putin of breaking international law with the “unacceptable Russian intervention in Crimea”.

Mr Putin defended Russia's action against “ultranationalist forces” in Ukraine during the conversation.

A Kremlin statement posted online said Mr Putin spoke with Mrs Merkel by phone today, and that he “directed her attention to the unrelenting threat of violence” to “Russian citizens and the whole Russian-speaking population”.

The statement said Mr Putin had stressed that measures taken by Russia so far were “fully adequate”.