The British Foreign and Commonwealth Office said it was advising against travel to Misurata, Tripoli and Ras Lanuf along the Egyptian border.
"The FCO advises against all travel to all other parts of Libya, including Benghazi," the warning read. "The British Office in Benghazi has temporarily suspended operations."
In January, the FCO said it was "aware of a specific, imminent threat to Westerners in Benghazi." Last month, the Italian government closed its diplomatic outpost in Benghazi after its envoy to Tripoli was attacked, but uninjured, when he left the consulate's grounds.
"Further threats and attacks against Westerners, Western interests and symbolic targets are possible," the British government warned. "These could include international hotels, the General National Congress building and other government and security institutions."
U.S. Ambassador to Libya Chris Stevens and three of his staff members died after a militant attack on the U.S. consulate in Benghazi last year.
U.S. and British forces helped with NATO operations in Libya in 2011. The Libyan government has struggled with internal security and political challenges since the end of the conflict.