German Chancellor Angela Merkel has called during a visit to Moscow for Russia to do more to persuade separatists in eastern Ukraine to abide by a cease-fire that has been strained in recent weeks.

Speaking alongside Russian President Vladimir Putin at a press conference, Merkel said the past week's creation of groups to negotiate a lasting settlement of the dispute provided a "glimmer of hope" but that progress was lacking elsewhere.

Ukraine says more than 8,000 people have died in the conflict that began in April 2014.

Merkel was the only prominent European leader to visit Russia over the weekend to mark the 70th anniversary of the surrender of Nazi Germany. On Sunday, she laid a wreath at the Tomb of the Unknown Soldier by the walls of the Kremlin.