Armenia and Azerbaijan have accused each other of violating a humanitarian ceasefire in the Nagorno-Karabakh region shortly after it came into effect.
The two former Soviet republics have been engaged in a flare-up over the disputed South Caucasus region of Nagorno-Karabakh, controlled for decades by Christian Armenian troops but considered by the United Nations as part of predominantly Muslim Azerbaijan.
Armenian military spokeswoman Shushan Stepanyan said on Monday evening that "the intensity of the fire along the border" of disputed region had "sharply increased," according to a statement on her Facebook page.
Azerbaijan's Defence Ministry in Baku had said earlier on Monday that its soldiers in the village of Safiyan were shot at.
The Armenian authorities in Nagorno-Karabakh rejected that claim and the Armenian Defence Ministry in Yerevan accused Azeri forces of targeted disinformation.
Azerbaijan's armed forces resumed artillery shelling 45 minutes after the ceasefire came into effect, a ministry representative in Yerevan said.
"I think we're, obviously, very deeply concerned by the reports that there are already ceasefire violations shortly after the parties agreed to implement their commitments for a third time in recent days," a spokesperson for UN Secretary General Antonio Guterres told journalists in New York on Monday.
"It is very important that the parties fully implement their agreement, and he expects them to abide by these commitments," the spokesperson said.
The latest attempt at a pause in fighting was agreed in Moscow and facilitated by the US.
It came into force at 8am local time on Monday.
Both countries had reaffirmed their commitment to the truce on Saturday, according to a joint news release from the US State Department.
The foreign ministers of the two countries are due to meet for talks in Geneva on Thursday, Azerbaijan's President Ilham Aliyev said in a televised address, adding, "we are not against negotiations."
They should make sense, however, and provide for the return of the territory under Baku's control.
Azerbaijan lost control of the mountainous area with about 145,000 inhabitants in a war after the collapse of the Soviet Union around 30 years ago.
A fragile ceasefire has existed since 1994.
Cultural, religious and historical ties link Azerbaijan to Turkey and similarly Armenia to Russia.
The recent heavy fighting over Nagorno-Karabakh flared up on September 27.
Australian Associated Press