Azerbaijan said Sunday it had agreed to extend a deadline for Armenia to withdraw from a disputed district as part of a peace accord that ended six weeks of fierce fighting over the Nagorno-Karabakh region.

Residents of the Kalbajar district in Azerbaijan, which has been controlled by Armenian separatists since a 1990s post-Soviet war, began a mass exodus in the days leading up to the initial withdrawal deadline on Sunday.

But a foreign policy adviser to Azerbaijan President Ilham Aliyev said his country had extended the deadline over humanitarian considerations.

Hikmet Hajiyev said the withdrawal of "Armenian armed forces and of illegal Armenian settlers" was delayed until November 25 following an appeal from Armenia and mediation with Russian President Vladimir Putin.

"Kalbajar's settlement by Armenians was illegal. The people who were resettled there have no property rights," Hajieyv told a news conference.

Kalbajar was almost exclusively populated by ethnic Azerbaijanis before they were expelled by Armenians in the 1990s war between the two countries over Nagorno-Karabakh, and a majority of the homes being abandoned previously belonged to Azerbaijanis.

Over the weekend AFP journalists saw fleeing residents haul away anything they could manage, including furniture, doors and windows.

In the Kalbajar village of Charektar, dozens of homes were set on fire by their former owners to make them unhabitable for the coming Azerbaijanis.

"We also moved our parents' graves," one Charektar resident said. "The Azerbaijanis will take great pleasure in desecrating our graves. It's unbearable."

The village looked like a ghost town on Sunday, abandoned to stray dogs. All that was left were charred, collapsed homes, damaged furniture and rubbish strewn across the ground.

 - Russian peacekeeping force -

 A Russian peacekeeping contingent deployed this week to Nagorno-Karabakh set up checkpoints and positions in the region's administrative centre Stepanakert.

The deployment was part of the peace deal, under which Armenia cedes swathes of territory that Azerbaijan's forces gained in the weeks of fighting.

The defence ministry said Sunday that over two days it had escorted more than 700 people returning to Stepanakert, which was shelled heavily during the fighting.

The ex-Soviet rivals finally agreed to end hostilities early last week after repeated efforts by Russia, France and the US to get a ceasefire fell through during the nearly two months of clashes.

A key part of the peace deal includes Armenia's return of Kalbajar, as well as the Aghdam district, by November 20 and the Lachin district by December 1, which have been held by Armenians since the devastating 1990s war which claimed 30,000 lives.

Hajiyev said Sunday the timetable for the Armenian withdrawal from the remaining districts was unchanged.

Armenia has said 2,317 of its fighters were killed in the clashes in which each side accused the other of targeting civilian infrastructure.

Azerbaijan has not revealed its military casualties, but Putin said the number of deaths on both sides surpassed 4,000 and that tens of thousands of people had been forced to flee their homes.

- Outrage over peace deal -

Before departing en masse, Armenians flocked to the Dadivank monastery nestled in a Kalbajar gorge for a final visit before it was ceded to Azerbaijan. AFP journalists witnessed a dozen women ask to be baptised at the religious site.

The peace accord with Azerbaijan has sparked a week of protests in Armenia, with demonstrators and opposition parties calling for Prime Minister Nikol Pashinyan to resign over the lost areas.

The former head of Armenia's national security service, Artur Vanetsyan, and several other suspects were arrested Saturday on charges of plotting to kill Pashinyan and seize power.

Lawyers of Vanetsyan, the head of the opposition centre-right Homeland party, called his detention a "persecution" and denied the allegations.

He was released from custody on Sunday evening after a Yerevan court ruled that his detention lacked legal grounds.

Karabakh's pro-Armenian separatists lost the key town of Susha during the fighting, and the evacuation of the bodies of those killed in the area continued on Sunday, under the protection of Russian soldiers. 

"I came to get the body of my nephew, who was killed in Susha," said a man of around 50. 

"His wedding ring was still on his finger -- apparently the bodies left on the battlefield were not desecrated."