KIEV, March 24 - Ukrainian government troops and separatist fighters have drawn closer to each other at several places along the tense front line in eastern Ukraine, Reuters reported, citing monitors.

The developments raise the risk of violent flare-ups that could wreck a shaky ceasefire.

At some points, the sides have drawn within shouting distance of each other.

The Organization for Security and Cooperation in Europe, which monitors a ceasefire agreed in the Belarus capital Minsk in 2015, says such advances violate the spirit of the accord.

Alexander Hug, deputy head of the OSCE mission, said its monitors struggle to verify if the accord is being respected because both sides refuse to disclose their units' locations and limit access to their positions.

"There is only one reason why the sides restrict us, it's because they do not want us to see what they are doing," he said.

With the two forces so close, the slightest movement on one side can provoke the other side into a violent reaction -- a scenario that caused one of the deadliest flare-ups of fighting in two years at the end of January.

The three-year-old conflict has killed more than 10,000 people, displaced 1.6 million and brought relations between Russia and the West to a level of hostility unseen since the Cold War. Pro-Russian separatists control a swathe of eastern Ukraine that they seized in 2014.

OSCE monitors say there is a risk of further flare-ups because forces loyal to Ukraine's government and the separatists are within such dangerous proximity.

"The Minsk agreements didn't say you can move up to the line and stand on each other's toes," said Hug. "As long as these root causes are not dealt with ... then a renewed escalation is just a matter of time."

He said the arrival of spring made it harder for monitors to verify the location of positions, because snow makes it easier to spot fresh fortifications from the ground or with drones.

The flare-up in the town of Avdiyivka earlier this year showed how easily new fighting can be provoked.

Intense shelling during the week-long escalation around the government-controlled town killed more than 40 soldiers, civilians and rebel fighters. Civilians were trapped with no heat in bitter cold after shelling halted a power station.

Both sides blamed the other for causing the fighting, and described it at the time as an attempt to test the new Trump administration by provoking clashes.

The U.S. government, including state department officials held over from the outgoing Obama administration, largely backed the Ukrainian position, blaming "Russian aggression" for the fighting.

Hug named five points on the front line most at risk of future clashes, including the area around Avdiyivka, nearby Horlivka and territory east of the government-held port city of Mariupol. These tallied with places where the Ukrainian defense official also described opposing forces drawing closer together. (rt/ez)