The latest developments raised doubts about the prospects of the new international push to end a month of clashes.
The latest ceasefire was agreed on Sunday after separate talks in Washington between US Secretary of State Mike Pompeo and the foreign ministers of Armenia and Azerbaijan.
Representatives of the Organization for Security and Co-operation in Europe (OSCE) Minsk Group led by France, Russia and the United States, also participated in the talks.
The group said, its co-chairs and the foreign ministers have agreed to meet again in Geneva on Thursday.