The US State Department has ordered all family members of embassy employees to leave Mali, amid the country's escalating conflict with Islamist militants who control the vast arid north.

The order late Friday follows a tumultuous week in which gunmen across the border in Algeria staged a deadly raid on a remote gas plant, taking an unknown number of foreign hostages.

"On January 18, the Department of State ordered the departure of all dependent family members who are not employed at the US Embassy in Bamako, Mali, for a period of up to 30 days," the notice stated.

It cited "ongoing fighting in northern and central Mali, fluid political conditions, the loss of government control of Mali's northern provinces, and continuing threats of attacks and kidnappings of westerners."

Mali also "continues to face challenges including food shortages, internally displaced persons, and the presence in northern Mali of factions linked to Al-Qaeda in the Islamic Maghreb (AQIM)."

And although conditions in the capital remain calm, "the recent escalation of hostilities around Mopti in northern Mali has heightened tensions throughout the country," the warning said, also noting that Interim President Dioncounda Traore had declared a state of emergency on January 12.

French troops joined a regional effort to oust the militants on January 11, after the Al-Qaeda-linked rebels swooped down from their northern stronghold and threatened the Malian capital Bamako.