British citizens have been warned to leave the African state of Mali unless they have "urgent business" there following a military coup.
In the north of Mali - part of the Sahara Desert - a rebellion by ethnic Tuaregs appears to be gaining ground.
The Foreign Office has changed its travel advice following a coup on 21 March and specifically warned people to be cautious in the capital, Bamako.
It is not thought many Britons are in the impoverished country.
Rebels from the National Movement for the Liberation of Azawad (MNLA) are trying to carve out a homeland for the Tuareg people.
The rebels have attacked the strategically important northern garrison town of Gao with heavy weapons, hours after another town, Kidal, fell to them.
The Foreign Office said: "We advise against all travel to Mali and you should leave if you have no pressing need to remain."
The Malian President, Amadou Toumani Toure, was toppled in the coup and replaced by army officers.
A night time curfew has been lifted but the Foreign Office said: "We continue to advise British nationals in Bamako to exercise caution and stay away from crowds and demonstrations when travelling around the city.
"There have been reports of some shops beginning to run low on supplies and of long queues forming outside some banks.
"Given ongoing instability in the country, and now that the airport has re-opened, you should leave if you have no pressing need to remain," he added.