In a telephone conversation Lavrov "stressed the need for urgent measures to de-escalate the situation in Ukraine, above all to stop military operations against protesters and to put an end to the aggressive activities of the ultra-nationalist Pravy Sektor," or Right Sector movement, Russia's foreign ministry said in a statement on Saturday.

The two men also discussed "the measures taken to resolve the situation" regarding a group of international OSCE observers who were abducted on Friday in eastern Ukraine.

In a separate statement, Russia's foreign ministry said Lavrov had held another phone conversation with the OSCE's current chairman, Swiss President Didier Burkhalter.

Burkhalter "thanked the Russians for their efforts to secure the release of the (OSCE) observers", the ministry said.

RA/MB