Armenia has accused Azerbaijan of violating a humanitarian ceasefire in the disputed region of Nagorno-Karabakh within minutes of it coming into force.
A truce had been agreed to start at midnight local time (20:00 GMT Saturday).
But an Armenian defence ministry spokeswoman said Azerbaijan broke the ceasefire after just four minutes by firing artillery shells and rockets.
Azerbaijan is yet to respond to the allegations.
The decision on the ceasefire was taken in line with agreements that led to a ceasefire being signed last weekend. However, clashes continued despite that accord.
Fighting flared last month over a region internationally recognised as part of Azerbaijan but which is run by ethnic Armenians. Hundreds have died.
This is the worst violence in the region since a six-year war over the territory ended with a ceasefire in 1994.