BERLIN-- German Chancellor Angela Merkel on Sunday held a phone talk with Russian President Vladimir Putin and called for substantial results in forming a contact group to find a political solution to the Ukraine crisis, German government spokesman Steffen Seibert said.

Merkel pointed out the urgency of establishing an international contact group which will find a political way to end the conflict in Ukraine, Seibert said in a statement.

The chancellor also stressed that the scheduled referendum in Crimea, an autonomous republic of Ukraine, is illegal and violates the Ukrainian constitution and international law, the statement added.

The mostly Russian-speaking Crimea, home to Russia's Black Sea Fleet, has become the epicenter of the ongoing crisis in Ukraine since President Viktor Yanukovych was ousted by parliament on Feb. 22.

The Crimean parliament on Thursday voted to become part of Russia. The parliament session also set a referendum on March 16, which would ask whether the Crimean people would like to remain part of Ukraine or join Russia.

Commenting on the simmering tensions in Crimea, Russia said Friday that they did not expect a new cold war and the West and Moscow could seek some common ground to solve the Ukraine crisis through dialogue.

Referring to the planned referendum, Russia said it reflected the common will of the Crimean people.

According to Seibert, Merkel also discussed the recent developments in Ukraine with Turkish Prime Minister Recep Tayyip Erdogan over phone on Saturday.

The two leaders stressed in a joint statement that the sovereignty, territorial integrity and political unity of Ukraine must be protected. They also noted the importance of forming a committee to investigate the "violent incidents that have happened in Ukraine in recent weeks."