During an official visit to London, Jean-Yves Le Drian suggested that France had an open-ended commitment to defend Mali from al-Qaeda in the Islamic Maghreb (AQIM), reports The Telegraph.
A French expeditionary force deployed in the country in January to recapture Timbuktu, Gao and Kidal – the three main cities in northern Mali – from AQIM and its allies.
At first, 2,500 soldiers were deployed on Operation Serval and Laurent Fabius, the foreign minister, promised on Jan 30 that they would leave "quickly".
Since then, the number of French troops in Mali has risen to almost 4,000 while the timetable for their departure has been revised. On current plans, half will leave by the end of July, when Mali holds a presidential election.
But Mr Le Drian said that a combat force would stay to prevent any "revival of terrorism". He added: "This is the reason why France will remain with roughly 1,000 troops on Malian territory for an undetermined period of time to carry out counter-terrorism operations if necessary."
Britain has deployed transport and surveillance aircraft to help the French in Mali. Mr Le Drian commended the "swiftness" of Britain's "logistical support and intelligence support", noting that it began on the second day of Operation Serval and "it hasn't stopped since".
The announcement came as Valerie Trierweiler, the French first lady, began a 48-hour tour of Mali, with a visit to Gao.
France's aim is to hand over responsibility for Mali's security to an African force of up to 11,000 men.
Read more of this report from The Telegraph.