Médecins Sans Frontières (MSF) has suspended mobile clinic activities outside the main towns in northeastern Central African Republic's (CAR) Vakaga province, following the killing of a woman in one of its ambulances.

The shooting, the medical charity said, followed a series of attacks and threats against humanitarian organisations and health workers in the past months. The woman was killed when an unidentified gunman fired on the vehicle on 10 March, it added.

The death was the second in recent months involving MSF. In June 2007, an MSF aid worker, Elsa Serfass, was killed by rebel gunfire in the northwest, leading to a significant reduction of MSF operations.

"We are shocked and outraged that our patient's mother was shot," Nicole Henze, MSF head of mission in CAR, said. "Our ambulance was clearly targeted, making us reconsider our activities in remote areas and our presence in the country. All armed persons are obliged to respect humanitarian aid. This includes medical personnel and, above all, our patients."

MSF has been providing basic healthcare to populations in remote areas of CAR, as well as referral and access to secondary care in more serious cases. Its teams have been operational in Ouham-Pendé, Ouham and Nana-Grébizi areas.

According to aid workers, continuing violence in northern CAR has led to the displacement of at least 290,000 civilians since 2005 and the "complete decimation" of public infrastructure.