The UN's refugee agency, the UNHCR, says it has been ordered to leave Uzbekistan within one month.
The agency said it had received a communique saying its entire office must shut, an order which it told the BBC was "a rare occurrence".
According to the agency, Uzbekistan's ministry for foreign affairs said the UNHCR, which has been in the country since 1993, had fulfilled its role.
The Uzbek authorities are yet to comment on the decision.
According to the UNHCR, the government statement said the agency had "fully implemented its tasks and there are no evident reasons for its further presence in Uzbekistan. With this regard, the ministry requests UNHCR to close its office in Tashkent within one month."
UNHCR spokesperson Astrid Van Genderen Stort told the BBC News website the decision "came as a surprise".
She said usually individuals were asked to leave a country rather than an entire office ordered to shut down.
The UNHCR said in a statement: "We are fully satisfied that our work in Uzbekistan has been performed in accordance with the mandate given to us by the UN General Assembly to protect and find solutions for refugees."
The agency's work in Uzbekistan currently focuses on the repatriation and resettlement of some 2,000 refugees, mainly from Afghanistan.
The UNHCR says it will abide by the government's order but would try to make alternative arrangements to meet the needs of refugees.