Armenia has accused Azerbaijan after a historic cathedral in Nagorno-Karabakh was shelled as fighting continued over the disputed region.
Photos showed damage to both the interior and exterior of the Holy Saviour Cathedral in Shusha city.
More than 300 people have died and thousands displaced since the latest fighting broke out on 27 September.
International monitors from the US, Russia and France have begun efforts to try and end the violence.
They are meeting the Azeri foreign minister in Geneva on Thursday. The Armenian foreign minister is due to meet his Russian counterpart in Moscow on Monday.Nagorno-Karabakh is officially part of Azerbaijan but run by ethnic Armenians. The current fighting is the worst seen in decades, and both sides have blamed each other for the violence.
What is the latest from Nagorno-Karabakh?
Shusha's Ghazanchetsots (Holy Saviour) Cathedral, an iconic site for the Armenian Apostolic Church, suffered serious damage, foreign journalists at the scene report.A section of the roof collapsed, rubble was strewn on the floor, pews were knocked over and the interior was covered in dust from parts of the building's limestone walls that had been hit.
A local resident, Simeon, told AFP news agency: "There is no military, nothing strategic here, how can you target a church? It is a very important cathedral for Armenians. God will be the judge."
Armenia's defence ministry spokesman, Artsrun Hovhannisyan, accused "enemy Azerbaijan" of targeting the cathedral.
Also on Thursday, Armenia announced it had dismissed the head of its National Security Service but did not give a reason for it.
For its part, Azerbaijan said its second-largest city, Ganja, and the region of Goranboy had been shelled by Armenian forces, killing at least one civilian.
What is the regional reaction to the fighting?
Iran, which borders Armenia and Azerbaijan, warned on Wednesday that the fighting had the potential to become a "regional war".
"Peace is the basis of our work and we hope to restore stability to the region in a peaceful way," President Rouhani said.
But he also said it was "totally unacceptable" for any stray shells and missiles to land on Iranian soil, following reports that shells had landed on Iranian border villages.
