Russian intelligence has acquired internal documents and dossiers from a spy, likely an OSCE staff member, reported ARD. The dossiers included personal information about staff susceptibility to alcohol and women.
"The Mission is concerned about any alleged breach of its security and is determined to examine all the allegations thoroughly in accordance with established procedures," the Ukraine mission said in a statement.
The dossiers, in particular, reportedly contained personal information about staff, including the types of women they were attracted to, their financial situation and whether they were susceptible to alcohol.
"Without proper verification, the OSCE … cannot comment or speculate on documents of unknown origin," the mission said. "However, the Mission is concerned that alleged breaches may carry a potential risk for its staff, compromising their privacy and security.
The OSCE monitoring mission in Ukraine is the largest field operation in the history of the organization. Its main task is to observe the conflict between Ukrainian forces and pro-Russia rebels.
Ukraine: Casualties of a low-level war
No end in sight
More than 10,000 people have been killed since pro-Russia forces launched a rebel insurgency in eastern Ukraine in 2014. Earlier that year, Moscow launched a military intervention and subsequent annexation of the Crimean Peninsula in an internationally-condemned referendum.
Despite German and French efforts to shore up support for a ceasefire deal known as Minsk II, fighting continues to erupt between Ukrainian forces and pro-Russia rebels. The mission said that over the past week, it recorded "more cease violations" than the previous reporting session.