The Swiss government says diplomat Heidi Tagliavini will step down as the representative of the Organization for Security and Cooperation in Europe (OSCE) in talks between Moscow, Kyiv, and pro-Russian rebels in Ukraine.
The Swiss Foreign Ministry said on June 6 that Tagliavini wants to give up her mandate soon but gave no exact date for her departure.
Tagliavini, who previously worked on crises in Chechnya and Georgia, has played a low-key role for the past year while mediating on the conflict in eastern Ukraine.
The announcement of her pending resignation comes four days after the latest talks ended.
Former Ukrainian President Leonid Kuchma, Kyiv's representative to the trilateral Contact Group on Ukraine, said he was thankful for the "constructive work" that Tagliavini did as the OSCE mediator.
OSCE officials have called for talks among the three sides to resume after the worst outbreak of fighting in the conflict since a February cease-fire deal was agreed to in Minsk.
At least 6,400 people have died in eastern Ukraine since April 2014.
Based on reporting by AP and Interfax