The leader of the self-declared Republic of Nagorno-Karabakh has said it will cease to exist in the new year.

Nazeli Baghdasaryan, a spokeswoman for Armenia's prime minister, said the number of refugees entering the country over the past week had reached 100,417, out of Nagorno-Karabakh's estimated population of 120,000.

The UN refugee agency (UNHCR) also stated that 100,000 people had fled, stating that many of those fleeing "are hungry, exhausted and need immediate assistance".

Artak Beglaryan, an Armenian former separatist official, said that "the last groups" of Nagorno-Karabakh residents were on their way to Armenia Saturday.

"At most a few hundred persons remain, most of whom are officials, emergency services employees, volunteers, some persons with special needs," he wrote on social media.

In addition to those killed during the Azerbaijani military operation, at least 170 people were killed in a huge explosion at a fuel depot in Nagorno-Karabakh on Monday.

It is not yet clear what caused the explosion near the main city of Khankendi, known as Stepanakert by Armenians.

The UN says it is sending a mission to Nagorno-Karabakh this weekend to assess the humanitarian situation, after Azerbaijan said it would allow such a visit to take place.

Armenia's ambassador-at-large, Edmon Marukyan, criticised the timing of the visit but stressed that it was important that UN officials saw for themselves what ethnic Armenians had been subjected to.

"It's good they will be there and they will become witnesses that these people were ethnically cleansed from their ancestral homeland, from their homes where their parents, where their ancestors were living and these people were totally cleansed from this territory," he told the BBC.

But he dismissed Azerbaijan's assurances as "a lie".

"It's total propaganda, another Azerbaijani fake propaganda. Nobody's going to stay in Nagorno- Karabakh," he said.