Armenia and Azerbaijan have accused each other of violating a new humanitarian ceasefire in fighting over Azerbaijan’s ethnic Armenian-controlled enclave of Nagorno-Karabakh early on Sunday.

The agreement came into force at midnight on Sunday (20:00 GMT Saturday).

Russia and France said they intervened in an attempt to mediate an end to the latest escalation in violence over the disputed region of Nagorno-Karabakh.

Shushan Stepanyan, a spokeswoman for Armenia’s defence ministry, said on Twitter that Azerbaijan had fired artillery shells and rockets in the early hours of Sunday.

The Azerbaijani Ministry of Defence later accused Armenia of not having observed the ceasefire.

Agreed on Saturday, the deal came a week after a failed Russia-brokered truce, which also saw the warring sides accusing each other of violations.

Russian Foreign Minister Sergey Lavrov called his Armenian and Azeri counterparts in the hours before the ceasefire was announced, his ministry said, urging both parties to adhere to the deal brokered in Moscow last week.

France also put out a statement after Saturday’s announcement, saying it followed “French mediation … in coordination with the co-chairs of the Minsk Group (Russia and the US)”.

The statement from the Elysee Palace also called on both sides to “strictly” respect the truce, adding that “France will pay great attention to that and will remain engaged for a lasting end to hostilities and a quick start of credible negotiations.”

Decades of conflict

The contested Nagorno-Karabakh region, a mountainous and heavily forested patch of land, is at the heart of a decades-long armed standoff between neighbours Armenia and Azerbaijan.

Home to some 145,000 people, Nagorno-Karabakh is controlled by ethnic Armenians backed by the Republic of Armenia, but is recognised as part of Azerbaijan under international law.

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Azerbaijan lost control of the area in a war that followed the collapse of the Soviet Union some 30 years ago. A fragile ceasefire had been in place since 1994.

Thousands of people have fled the region, predominantly inhabited by ethnic Armenians, since fighting flared up again on September 27.

The Armenian defence ministry said that more than 600 soldiers had been killed since then.

Azerbaijan has so far not provided any information on losses in its armed forces but it says that more than 50 civilians were killed in Armenian attacks.

Al Jazeera’s Bernard Smith, reporting from Yerevan, the Armenian capital, said it was Armenia that had pushed for the latest ceasefire.

The Armenian government was under enormous pressure because of the large number of casualties, as well as the loss of territory, he explained.

“The Azeris have taken, as we understand, territory that is essentially in the buffer zone between Nagorno-Karabakh and Azerbaijan. This is territory that Armenia has controlled since the 1994 ceasefire. Armenia considers it a buffer zone, a security zone, but it is Azeri territory. And for the last 26 years at least, both sides were supposed to have been negotiating the future of this territory as well as Nagorno-Karabakh,” said Smith.

“The Azeris say after 26 years, nothing has been done, there has been no solution, as to what to do with this territory, and so with Turkey’s support, they’ve been moving militarily. And they’ve succeeded in taking territory. Hence, the Armenians’ enthusiasm to push for a ceasefire.”