LACHIN, Azerbaijan -- A United Nations mission arrived in Nagorno-Karabakh on Sunday, Azerbaijan said, after almost the entire ethnic-Armenian population fled since Baku recaptured the breakaway enclave.

An Azerbaijani presidency spokesman told AFP that a "UN mission arrived in Karabakh on Sunday morning" -- mainly to assess humanitarian needs.

It marks the first time in about 30 years that the international body has gained access to the region.

Armenian separatists, who had controlled the region for three decades, agreed to disarm, dissolve their government and reintegrate with Baku following a one-day Azerbaijani offensive last week.

France has lashed out at Azerbaijan for only allowing the UN mission in after most residents had already fled.

The end of Karabakh's separatist bid dealt a heavy blow to a centuries-old dream by Armenians of reuniting what they say are their ancestral lands, divided among regional powers since the Middle Ages.

Nearly all of Karabakh's estimated 120,000 residents fled the territory over the following days, sparking a refugee crisis.

An AFP journalist at a border crossing along the Lachin corridor that links Karabakh with Armenia, saw only one car arrive from the now deserted enclave.

Sergei Astsaryan, 40, said he was among the last Armenians to leave the region.

"I have no idea of where to go, maybe Europe," he told AFP, adding however that he hoped many of the refugees would return if Azerbaijan "gives guaranties, provides help."

"I've talked to Azerbaijani police and they said there would be no problems if we want to return, that we can live in our homes."

Nazeli Baghdasaryan, spokeswoman of the Armenian prime minister, said "100,483 forcefully displaced persons arrived in Armenia" by Sunday morning.

She said 45,516 refugees were now in temporary accommodation.

- 'Sacred land' -

On Sunday, Armenia observed a national day of prayer for the region.

Bells tolled in churches across the country, and the head of the Armenian Apostolic Church, Karekin II, lead a service in the nation's main cathedral Echmiadzin, close to the capital Yerevan.

Clergymen in ornate robes sang ancient chants at an open-air altar outside the imposing cathedral built in a pale pink limestone.

"As our sacred land of Karabakh is deserted, we pray for our sisters and brother of Karabakh who are going through terrible suffering," said the pontiff.

Hundreds attended the religious service in the church of Saint Sarkis, in Yerevan.

"One of the most tragic pages of Armenian history is being written today," 28-year-old Mariam Vartanyan told AFP, standing in the crowd of worshippers wrapped in the smoke of burning incense.

- Ethnic hatred -

Yerevan has accused Baku of "ethnic cleansing" -- an allegation that Baku rejected -- calling on Armenians not to leave their homes and reintegrate with Azerbaijan where their rights would be respected.

Armenia, a country of 2.8 million, faces a major challenge housing the sudden influx of refugees.

The International Federation of Red Cross and Red Crescent Societies on Friday announced an emergency appeal for 20 million Swiss Francs ($22 million) to help those fleeing.

Azerbaijan is now holding "re-integration" talks with separatist leaders while, at the same time detaining some senior figures from its former government and military command.

Azerbaijan's Prosecutor General Kamran Aliyev said criminal investigations had been initiated into war crimes committed by 300 separatist officials.

"I urge on those persons to surrender voluntarily," he told journalists on Sunday.

Azerbaijani President Ilham Aliyev and Armenian Prime Minister Nikol Pashinyan are set to meet on Thursday in the Spanish city of Granada for Western-mediated talks aimed at ending their historic enmity.

With the two countries' relations poisoned by ethnic hatred ensuing from three wars in as many decades, several rounds of negotiations mediated by Brussels and Washington have so far failed to bring about a breakthrough.