Armenia and Azerbaijan traded accusations on Sunday of violating the new truce in their destructive conflict over the disputed region of Nagorno-Karabakh, despite a second attempt at a ceasefire.

The latest truce, which was announced on Saturday and took force at midnight, was the second attempt to establish a ceasefire since heavy fighting between Armenian and Azerbaijani forces broke out in Nagorno-Karabakh on Sept 27. The fighting and shelling has killed hundreds of people — both combatants and civilians — and marks the biggest escalation of a decades-old conflict over the region in more than a quarter-century.

Armenian military officials on Sunday reported artillery shelling and missile strikes by Azerbaijani forces carried out in the conflict zone overnight. In the morning, “the enemy launched an attack in the southern direction” of the conflict zone, and there were “casualties and wounded on both sides”, Armenian Defence Ministry spokeswoman Shushan Stepanian said.

Azerbaijan’s Defence Ministry, in turn, maintained that Armenian forces used mortars and artillery in the conflict zone overnight despite the ceasefire and in the morning attempted attacks in several directions. The ministry also accused Armenia of using large-caliber weapons to attack the positions of the Azerbaijani army in two regions north of Nagorno-Karabakh along the border between the two countries — a claim Armenian military officials denied.

Nagorno-Karabakh lies within Azerbaijan but has been under the control of ethnic Armenian forces backed by Armenia since a war there ended in 1994.

According to Nagorno-Karabakh officials, 673 of their servicemen have been killed in the renewed fighting. Azerbaijan hasn’t disclosed its military losses, but says 60 civilians have died so far and 270 have been wounded.

The recent fighting, involving heavy artillery, rockets and drones, has continued despite repeated calls for cessation of hostilities coming from around the globe. The escalation of fighting raises the spectre of a wider conflict that could draw in Russia and Turkey and threaten Caspian Sea energy exports.

Turkey has publicly backed oil-rich Azerbaijan in the conflict and vowed to help it reclaim its territory.

Russia, which has a security pact with Armenia but has cultivated warm ties with Azerbaijan, hosted top diplomats from both countries last week for more than 10 hours of talks that ended with the initial ceasefire agreement. But the deal frayed immediately after the truce took effect last Saturday, with both sides blaming each other for breaching it.

The new ceasefire agreement was announced a week later on Saturday, following Russian Foreign Minister Sergey Lavrov’s calls with his counterparts from Armenia and Azerbaijan, in which he strongly urged them to abide by the Moscow deal.

Later on Sunday, Armenia and Azerbaijan reiterated their commitments to the ceasefire in statements issued by their foreign ministries, and laid the blame for the breaches on each other.

Azerbaijan “reserves its right to take counter measures to protect its civilians and positions”, the country’s Foreign Ministry said.

Yerevan “will continue to undertake all necessary measures to impose peace on Azerbaijan and establish a ceasefire regime which will entail precise and effective mechanisms for maintaining and verifying it”, Armenian Foreign Ministry said.