KIEV, Nov. 11 - A soldier has been killed and five others wounded in separatist attacks in eastern Ukraine, a rise in violence that is threatening the region's delicate truce, AP reported.

Col. Andriy Lysenko, presidential spokesman for the military operation against the separatists, said Wednesday the casualties came amid 21 separatist violations of the cease-fire over the past day, including mortar attacks.

A cease-fire was agreed to in February, but did not appear to take real hold until the beginning of September, when both sides agreed to halt shooting on the first day of the new school year. They then agreed to pull back smaller-caliber artillery, bolstering an earlier heavy weapons pullback.

In September, the latest in a string of Western-brokered ceasefire agreements went into force, pushing fighting to its lowest level since close to the start of the conflict.

Officially the warring sides insist they have been withdrawing weapons, with Ukraine's military on Saturday saying it has pulled their 82-mm mortars back from the frontline, following similar declarations by pro-Moscow rebels.

On the ground however, each side is accusing the other of firing at soldiers and civilians, underlining the fragility of the truce that some fear could disintegrate like previous ceasefires.

In the village of Pisky, the closest Ukrainian position to the ravaged rebel-controlled Donetsk airport, soldiers report combat injuries every day.

Military spokesman Vladyslav Seleznyov accused the rebels of trying to "provoke us to return fire to disrupt the truce" and to "distract OSCE observers from the fact that they are not pulling back heavy weapons."

Kiev suspects that rebels are worried about the next step of the ceasefire agreement signed in Minsk in February, which requires them to give control of the Russian border back to Ukrainian authorities.

On the rebel side, Donetsk People Republic's officials say attacks could be launched by rogue Ukrainian forces.

"Battalions that are not under Kiev's control shot at Donetsk," said DNR defense ministry spokesman Eduard Basurin. "They are doing it on purpose, provoking us to respond," he told AFP. (ap/afp/ez)