Accused of giving away Ukrainian army positions to pro-Russian rebels, the agency tasked with monitoring the ceasefire in eastern Ukraine is denying the charge, saying its observers are impartial. Charges that the locations of Ukrainian units have been given to their foes have surfaced more than once since the Organization for Security and Co-operation in Europe began overseeing the conflict zone last year.

"I can tell you that our colleagues are working in a very close team,” Michael Bociurkiw, head of the OSCE’s Special Monitoring Mission in Ukraine, told Ukrainian TV Wednesday. “When they arrive, they undergo a lot of training, and they sign a code of conduct. ... They’re working in a close team, they all keep secrets, [and] no one gives information to a third party.”

The accusation came from a member of the Ukrainian Parliament's Committee on National Security and Defense, who said Russian-backed militants had fired on Ukrainian positions immediately after OSCE representatives had visited them.

According to Bociurkiw, the OSCE has 500 observers working in Ukraine. Of those, 24 are from the Russian Federation. But he was quick to say their nationality didn’t matter. "All the people working in the OSCE special mission are working on a special mission, and not for the country from which they came," Bociurkiw said.

On the other side, the OSCE has been accused of a pro-Ukraine bias. In November, the Russian Foreign Ministry said the multinational agency was reporting rebel troop movements but ignoring Ukrainian ceasefire violations.

"Some aspects of the recent work of the OSCE Special Monitoring Mission to Ukraine are a cause for concern," the Kremlin said in its statement (in Russian).

"We get the impression that its efforts are directed at helping and supporting only one side in the conflict, the official authorities in Kiev. ... Such policies from the mission's leadership undermine trust in its work."

The OSCE’s overall mission is to bring peace to the contested Donetsk and Luhansk regions. It has complained that it is being denied access to some areas of the conflict zone.