The OSCE says that its SMM is a civilian monitoring mission / Photo from UNIAN

"The Mission takes such allegations seriously; however, at this moment we have no evidence to support these claims. As such, the SMM will not comment on these allegations at the moment, but is reviewing the situation," the OSCE SMM said in a statement on Monday.

Presently, the OSCE Special Monitoring Mission to Ukraine includes international monitors originating from more than 45 countries, as well as 305 national staff, it said.

According to the OSCE SMM, any serious violation of the Code of Conduct, to which all mission members agree when they join the organization, leads to an immediate dismissal of the member of the mission. "On rare occasions we have already taken such decisions, and if required in future we will do so again," the statement said.

Read alsoHostile locals in occupied Horlivka confront OSCE monitorsThe OSCE says that its SMM is a civilian monitoring mission, with a mandate that does not include any intelligence gathering activity and operates on the principals of transparency and impartiality.

The FSB earlier announced the arrest in Russia of an alleged SBU agent who worked as interpreter for the SMM in Ukraine and allegedly gathered intelligence for the Ukrainian secret services.

The FSB named his identity, saying his name is Artem Shestakov, born in 1984.