"I appeal to all sides of the conflict in eastern Ukraine to adhere to their commitments and resume without further delay their contacts and consultations aimed at the full implementation of the Minsk arrangements in conformity with their letter and spirit," Burkhalter was quoted as saying on the OSCE website.
He also urged to release all hostages and illegally detained persons, withdraw armed formations, foreign troops and their equipment, and resort to a political dialogue.
The Kiev forces and the independence supporters of Ukraine's eastern regions have been in the state of military confrontation since mid-April, when the Kiev government launched a military operation in the east of the country.
In September, the warring sides reached a ceasefire agreement in Minsk, but since then they repeatedly accused each other of the truce violation. Another Contact Group meeting on the Ukrainian crisis settlement was expected to take place on December 12, but was reportedly postponed to December 19 over prisoner exchange issues.
