Observers from a European security organization have criticized the Ukrainian government for restricting freedom of movement of residents in the war-torn east by introducing permits for crossing the front line.

More than 6,100 people have been killed and 1.5 million displaced by the ongoing conflict between Russia-backed separatists and government troops.

The Kiev government in January introduced permits for crossing the contact line between the warring parties in a bid to prevent the spread of separatism to other regions in Ukraine.

The Organization for Security and Cooperation in Europe in a report published on Wednesday lambasted the system for making it hard for residents to leave the war-torn areas or get access to humanitarian aid.

Associated Press reporters have observed an inconsistent application of the permit system, affecting local residents.