ISTANBUL — Russia and Turkey have called for a cease-fire in Libya to begin this weekend, stepping in on Wednesday to try to resolve a conflict that Western powers and the United Nations have struggled to end.

Analysts say the Russians and Turks are seeking to exploit a diplomatic void left by Europe’s failure to end the fighting in Libya. A German-led effort to hold an international conference on Libya has come to nothing, and the United Nations Security Council has not called for a cease-fire.

The Russian and Turkish foreign ministers issued a joint statement calling for the cease-fire on Wednesday after President Vladimir V. Putin and President Recep Tayyip Erdogan met and presided over the inauguration of the TurkStream gas pipeline in Istanbul.

It is not clear how much Russia and Turkey can influence events on the ground, but Mr. Putin and Mr. Erdogan have met regularly to discuss military deployments in Syria, and have declared Libya a priority.