"The meeting has begun," the source said.
The Trilateral Contact Group, comprising Russia, Ukraine and the Organization for Security and Co-operation in Europe (OSCE), is working toward a diplomatic resolution of the ongoing armed conflict in Ukraine.
Earlier in the day, Ukrainian President Petro Poroshenko called on the Contact Group to discuss the implementation of the Minsk II ceasefire agreements, signed in mid-February by Kiev and the self-proclaimed republics of Donetsk and Luhansk.
Currently, OSCE observers are verifying and assisting, with the support of the Contact Group, in maintaining the ceasefire regime and the pullout of heavy weaponry from the region.
According to UN estimates, over 6,000 people have been killed in the conflict that erupted in April 2014.
