The move comes as more than 100,000 people have fled the Nagorno-Karabakh region - equivalent to almost the entire population of the ethnic Armenian enclave - since Azerbaijan seized the region last week.
ADVERTISEMENTA United Nations mission arrived in the Nagorno-Karabakh region on Sunday - for the first time in three decades.
Azerbaijan announced the arrival as the majority of the ethnic Armenian population fled the enclave after its recapture by Baku.
A spokesperson for the Azerbaijani presidency told AFP that the UN mission had arrived early on Sunday with the main task of assessing the humanitarian needs on the spot.
Earlier, the UN announced that it had received the green light to send a mission to the territory this weekend.
Armenian separatists, who have controlled Nagorno-Karabakh for three decades, capitulated and agreed to lay down their arms last week, after a lightning offensive by Azerbaijan to reconquer the territory.
In total, nearly 600 deaths have been reported in the wake of this military offensive, with the fighting itself said to have killed around 200 soldiers on each side.
Since then, the enclave has been almost entirely deserted by its inhabitants, with more than 100,000 refugees having fled to Armenia for fear of reprisals from Azerbaijan - raising fears of a serious humanitarian crisis.
On Sunday, Armenia, a region with a Christian majority, observed a day of prayer for Nagorno-Karabakh as church bells rang out across the country.
The separatist enclave, supported militarily and economically by Yerevan, opposed Baku for more than three decades, notably during two wars between 1988 and 1994 and again in the autumn of 2020.