Britons living in Libya should leave the country immediately because of the "greater intensity of fighting," the Foreign and Commonwealth Office (FCO) has warned.
The department warned that violent clashes between armed groups are possible across the country, including in the country's capital Tripoli, particularly at night.
They said: "Fighting can break out in many places and at short notice. It can become serious quickly putting those in the area at risk. You should remain vigilant at all times."
They added: "Keep a low profile and try to limit travelling around as much as possible, particularly at night. There is a high threat from crime."
There are believed to be between 100 and 300 Britons in the north African country.
Tripoli International Airport was closed a fortnight ago following clashes between armed groups nearby, but any Britons remaining should use "commercial means" to leave, they said.
The British Embassy remains open but with reduced staff and a limited ability to provide consular assistance.
More top news
Nearly 500 identity frauds were reported every day in the first half od this year.
New position paper argues that it will be 'unnecessary' for the European Court to have direct jurisdiction in Britain after Brexit.
Demands for the government to deliver a fair deal on transport for the north of England will be made by political and business leaders.