Pro-Russian rebels fighting in eastern Ukraine have agreed to begin pulling heavy weapons from the front line of the conflict, according to a Russian general involved in implementing the ceasefire, cited by the BBC.

General Alexander Lentsov said the rebels had signed orders to complete the withdrawal over the next two weeks, starting from Sunday. The authorities in Kiev have not said whether they will follow suit, but Lentsov reportedly said that the government had been informed of the rebel's intentions.

A ceasefire brokered by France and Germany came into effect Feb. 15, but fighting has continued, particularly in the strategic transport hub of Debaltseve. The rebels seized the town in the week after the ceasefire came into effect, saying they did not believe that it was covered by the agreement.

Each side has accused the other of violating the truce. The pullback of heavy weapons from the front line had been due to start Feb. 17 and be completed by March 3.

News of the move came as the rebels and Kiev conducted a prisoner swap Saturday. A Reuters reporter in the village of Zholobok said that they observed over 130 Ukrainian government troops exchanged for 52 rebels.

The exchange represents one of the first significant moves to implement the terms of the peace deal which has been carried out successfully.

Reflecting on the state of affairs in Ukraine, U.S. Secretary of State John Kerry said Saturday that the U.S. was considering additional sanctions against Russia, calling the country's actions “unacceptable”.

"We are confident that over the next few days we are going to make it clear that we are not going to play this game, not going to sit here and be part of this extraordinarily craven behavior at the expense of the sovereignty and integrity of a nation,” he said, according to a CNN report.

Almost 5,700 people have been killed since the fighting erupted in April 2014, and some 1.5 million people have fled their homes, according to the UN.