Pro-Russian fighters in Ukraine on Friday announced that they will reject further peace talks, signaling further instability at the end of deadliest week of the conflict.

"Attempts to talk about a cease-fire will no longer be undertaken by our side," the Associated Press reports the main separatist leader, Alexander Zakharchenko, as saying.

The New York Times adds:

“We will attack” until the Ukrainian Army is driven from the borders of the Donetsk region, Aleksandr Zakharchenko, the leader of the Donetsk People’s Republic rebel group, said in comments carried by Russian news agencies. Referring to the Ukrainian government, he said, “Kiev doesn’t understand now that we can attack in three directions simultaneously.”

The news comes as the UN's Office of the High Commissioner for Human Rights states that over 5,000 people have been killed and over 10,000 wounded since the conflict broke out last year.

OHCHR spokesman Rupert Colville said at a press conference that the period between between January 13 and 21 when an average of 29 people were killed per day "has been the most deadly period since the declaration of a ceasefire on 5 September." That ceasefire, as the Washington Post notes, "was always tenuous, and recent clashes have dealt serious blows to efforts to prevent its full collapse."

On Wednesday, when the latest round of peace talks was taking place in Berlin, U.S. Army Europe head Lt. Gen Ben Hodges said in Kiev that a yet-to-be-determined number of U.S. soldiers would be heading to Ukraine in spring to train the Ukrainian National Guard.