Armenia and Azerbaijan have accused each other of violating a humanitarian ceasefire in the disputed region of Nagorno-Karabakh.
Both sides agreed had agreed a truce 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 later said Armenia had broken the truce, reports BBC.
Both countries signed a Russian-brokered ceasefire last Saturday. However, clashes continued despite that accord.
Fighting flared last month over the territory, which is internationally recognised as part of Azerbaijan but 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.
Earlier on Saturday, both nations continued to trade accusations over violations of the Russian-brokered truce agreed last weekend and doubts are likely to remain following the latest statements.