Given the availability of weapons and a close proximity of forces, the Donbas is like a powder keg, Hug said.
He believes urgent steps need to be taken to reduce the level of military escalation in the Donbas.
While patience is coming to an end, and the level of anger is building, there is no time left for hypotheses and assumptions, the monitor stressed.
He said that the parties should remove all heavy weapons beyond the agreed withdrawal lines and disengage forces being too close to each other. Hug underscored this should be done without any evasions and delays.
As previously reported, OSCE observers deployed at two Russian checkpoints in an uncontrolled part of the Russian-Ukrainian border recorded 104 people in military-style outfits crossing the border in both directions. 48 of them crossed into the Russian Federation, 56 into Ukraine.