Much of Nagorno-Karabakh's ethnic Armenian population flees as first UN mission in 30 years set to arrive

At least 100,000 people have now fled the breakaway region of Nagorno-Karbakh - more than four-fifths of the population - since Azerbaijan reclaimed the territory in a lightening offensive, authorities in neighboring Armenia said.

The rapid exodus has prompted the United Nations to send its first mission to the territory in about 30 years.

Stephane Dujarric, the spokesman for the UN Secretary-General, said the UN team on the ground would "identify the humanitarian needs for both people remaining and the people that are on the move."

Though internationally seen as part of Azerbaijan, the Armenian-majority Nagorno-Karbakh had spent decades under the control of a separatist, de facto government until Azerbaijan's victory last week. The former breakaway republic will cease to exist as of next year.

Azerbaijan has long been clear about the choice confronting Karabakh Armenians: Stay and accept Azerbaijani citizenship, or leave.

As of Saturday morning, 100,417 people had been "forcibly displaced," the Armenian prime minister's spokeswoman, Nazeli Baghdasaryan, told reporters.

Armenian authorities have responded to the outflux of people by asking the International Court of Justice, a judicial arm of the UN, to tell Azerbaijan to withdraw its troops - citing fears of "punitive actions."