"The sides need to demonstrate their commitment to deliver on their promises, and work in good faith with the SMM [Special Monitoring Mission] if they wish to have a verification system that builds trust, and contributes to a de-escalation in conflict that people on both sides of the line can see and hear for themselves," Alexander Hug said in an interview with RIA Novosti.
He underscored that only the sides to the eastern Ukrainian crisis can bring the conflict to an end.
"They have agreed the Minsk Package of Measures which include an immediate and comprehensive ceasefire; withdrawal of all heavy weapons; and ensuring effective monitoring and verification by the OSCE," Hug said.
Despite several rounds of peace talks and a ceasefire agreement between Kiev forces and Donbas militia reached in February, the fighting in eastern Ukraine continues.
Minsk peace accord signed by the warring sides in February also stipulated heavy weaponry withdrawal and granting Donetsk and Luhansk regions more autonomy. However, both sides have repeatedly accused each other of violating the peace deal.
The SMM was deployed to Ukraine in March 2014 at the request of the Kiev authorities, with its mandate extended until March 2016.
