Kavita Belani, UNHCR representative in Armenia, told a U.N. press briefing by video link that huge crowds of tired and frightened people were gathering at registration centres.
"This is a situation where they've lived under nine months of blockade," she said. "And when they come in, they're full of anxiety, they're scared, they're frightened and they want answers."
"We are ready to cope with up to 120,000 people. It's very hard to predict how many will come at this juncture," she added in response to a question about refugee numbers.
Nearly a third of the refugees are children, another UNHCR official told the briefing. "The major concern for us is that many of them have been separated from their family," said Regina De Dominicis, UNICEF regional director.
International Federation of Red Cross and Red Crescent Societies representative Hicham Diab said there was a massive need for mental health support for refugees.
(Reporting by Emma FargeEditing by Miranda Murray)

A woman walks in front of a shop with portraits of Azerbaijani soldiers fallen during the armed Nagorno-Karabakh conflict in 2020, outside Baku, Azerbaijan, 08 September 2023. The Nagorno-Karabakh conflict escalated in 1992 between two former Soviet Republics on the territory of Azerbaijan in the self-proclaimed Republic of Artsakh / Nagorno-Karabakh Republic with its capital in the city of Stepanakert (Armenian name) or Xankendi (Azerbaijani name) where predominantly Armenians live. The conflict resulted in thousands of deaths, refugees on both sides and a frozen conflict for many years. In 2020, during another escalation and hostilities, Azerbaijan took control of large areas of Nagorno-Karabakh. After this a ceasefire agreement was concluded and Russian peacekeepers were introduced into the conflict zone. Currently, there is an escalation on the line of contact, shelling of positions, and a build-up of military potential on both sides. Azerbaijan and Armenia accuse each other of violating the agreement. EPA-EFE/MAXIM SHIPENKOV ATTENTION: This Image is part of a PHOTO SET