The agreement with the co-chairs of the OSCE Minsk Group has not reached what would have been a fourth truce since the fighting began on September 27.
The toll of the worst fighting in the South Caucasus in more than 25 years has passed 1,000 dead.
Nagorno-Karabakh is internationally recognized as part of Azerbaijan, but it is populated and controlled by ethnic Armenians.
About 30,000 people were killed in a 1991-1994 war in the region.
Azerbaijan rejects any solution that would leave the Armenians in control of the enclave, which it considers to be illegally occupied. Armenia considers the territory to be part of its historic homeland and says the people need its protection.
The Nagorno-Karabakh Emergency and Rescue Service said the central market in Stepanakert, the largest town in the enclave, had come under fire and large parts of it had been set on fire.
Armenian Defense Ministry spokesman Shushan Stepanyan also said several civilians were injured in attacks on the strategic town of Shushi, 15 km south of Stepanakert.
The Azerbaijani Defense Ministry denied both charges, adding that the areas of Terter, Aghdam and Aghjabedi had been under artillery fire, as had Gubadli, a town between the enclave and the Iranian border which was taken. this week by Azeri troops.
Speaking from Yerevan, Al Jazeera’s Rory Challands said videos released by Nagorno-Karabakh authorities and the Armenian Foreign Ministry showed starbursts over the hills, which “tells us. – it is white phosphorus used by the Azerbaijani army ”.
“Under international law, white phosphorus is prohibited for use in the presence of civilians and restricted against military personnel. The Armenian authorities claim that this use is illegal, ”he said.
Speaking from Baku, Al Jazeera’s Hoda Abdul-Hamid said Azerbaijan “has rejected these allegations as being without foundation”.
“The Defense Ministry said in a tweet that the military does not possess any type of weapons or ammunition prohibited by international law,” she said.
The ministry said Armenia had transported white phosphorus to the region, Abdul-Hamid added.
Russian help requested
Armenian Prime Minister Nikol Pashinyan has officially called on Russian President Vladimir Putin to start “urgent” consultations to ensure security in a conflict with Azerbaijan, the foreign ministry said on Saturday.
In his letter to Putin, Pashinyan said hostilities approached Armenia’s borders, reiterated Turkey’s support for Baku, and invoked a 1997 treaty on friendship, cooperation and mutual assistance between Moscow and Yerevan. .
“The Prime Minister of Armenia has called on the Russian President to start urgent consultations with the aim of determining the type and amount of assistance that the Russian Federation can provide to Armenia to ensure its security,” he said. Ministry of Foreign Affairs.
Moscow’s defense pact with Armenia does not extend to Nagorno-Karabakh, however, and Russia said on Saturday that “necessary” aid would only be provided if the fighting reached Armenian territory.
At the same time, Foreign Ministry spokeswoman Maria Zakharova said “concrete formats” of assistance to Armenia would be discussed.
Russia has a military base in Armenia’s second largest city, Gyumri.
The Russian Foreign Ministry also called on the warring parties to immediately cease fire and start “substantive” talks.
In an apparent warning to Moscow, Azerbaijani President Ilham Aliyev said on Twitter that “we don’t want third countries getting involved.”
“It’s a fight between us and Armenia,” he added.
Total name of morts
More than 1,000 Nagorno-Karabakh army fighters have been killed. Azerbaijan did not disclose its military losses.
Russia has estimated as many as 5,000 dead on both sides of the conflict.
Three truces have failed to stop the fighting, the most recent negotiated last Sunday in Washington, DC by US Secretary of State Mike Pompeo.
The OSCE Minsk Group, formed to arbitrate the conflict, said Armenia and Azerbaijan had also agreed to exchange the bodies of fighters and provide lists of prisoners within a week. war detainees, with the aim of a possible exchange.