The rebels today also reported increased shelling from government forces and the death of one of their fighters.
The fighting that broke out in eastern Ukraine two years ago has killed more than 9,100 people and left territory under rebel control.
A cease-fire agreement signed last year has significantly reduced the violence, but it is regularly violated by both sides and the political settlement has not been implemented.
The Organization for Security and Cooperation in Europe says in its most recent report that its observers recorded a slightly higher number of cease-fire violations on Thursday compared with the previous day, including in Avdiivka.