The deputy head of the international monitoring mission in eastern Ukraine has upbraided both sides in the conflict as not fully committed to the truce.

Alexander Hug of the Organization for Security and Cooperation in Europe's monitoring mission said Wednesday that during a two-day inspection trip in both rebel- and government-held territories, there was no gunfire.

"I don't see any excuse" for the Ukrainian forces and Russia-backed rebels to violate the cease-fire, he said. "They can hold their fire, because they can do it for hours while I'm there."

Hug told a news conference in the government-held port city of Mariupol that he met with the Ukrainian and Russian generals on the conflict's Joint Control Commission and agreed "the situation has deteriorated."