Right Sector militants disrupted the work of the OSCE Monitoring Mission (SMM) in Donbass, the observers said in a report.
Armed Right Sector members denied the SMM's access to Avdeevka, 15 kilometers North-West of Donetsk, when the group was en route to a JCCC (Joint Center for Control and Coordination) observation post.
The SMM appealed to the Ukrainian Armed Forces Major General, head of the Ukrainian side to the JCCC, but the Right Sector members persisted and said they obeyed the orders of their own commanders and "did not fall under the command of the Ukrainian Armed Forces."
Earlier in June, the Right Sector barred OSCE monitors from entering the Communist Party office in the southern port city of Odessa after having seized it.
The Right Sector is a hardline nationalist union infamous for committing numerous human rights violations.
The Kiev authorities have been unsuccessfully trying to rein in militarized volunteer formations such as the Right Sector.