KIEV, Ukraine - Russia-backed rebels in east Ukraine say that they are pulling back heavy artillery from front-line positions in response to similar moves by the Ukrainian army, a first step toward satisfying a truce agreement signed last week.

Rebel leader Alexander Zakharchenko told Interfax news agency Tuesday that his forces were withdrawing heavy artillery from certain areas on the front line, but said that "in those places where Ukraine does not withdraw its artillery, we also will not withdraw."

The withdrawal would be an important step toward implementing a new peace agreement signed Saturday, which requires both sides to remove heavy artillery from the front line. The withdrawals would create a buffer zone and allow a Sept. 5 cease-fire, which has been riddled by violations, to be more effectively enforced.