Mauritania said on Tuesday it had sent exterminators to the north to fight a plague of locusts swarming over the desert which could devastate the West African nation, local media said. "The situation is characterised by the presence of large swarms of winged locusts and larvae," said Mohamed Abdullahi Ould Babah, head of the centre for controlling the desert locust, according to the AMI news agency.

He told a meeting of international partners involved in locust control that treatment and observation teams had already cleared more than 50 square kilometres (19 sq miles) of easily accessible terrain. Ould Babah said the winter rain expected from November 15 could make the task more difficult and warned that many high-risk parts of the north were inaccessible, AMI said.

After becoming airborne, swarms of tens of millions of locusts can fly up to 150 kilometres (93 miles) a day with the wind behind them, stripping whole fields of their crops.

Mauritania, which is three-quarters desert, suffered a large locust attack in 2004 covering about 16,000 square kilometres that ravaged a vast quantity of crops and threatened nearly a million people with starvation.