BOKO HARAM extremists have overpowered a multinational military force and seized its key base on Nigeria’s border with Chad, fleeing residents reported today.

Scores of soldiers and civilians were killed, while others drowned in Lake Chad, said the residents, many of whom had taken to canoes to cross the lake.

They reported that the Islamist insurgents had fired rocket-propelled grenades and automatic assault rifles and hurled explosives.

“They came in their hundreds, driving several Hilux patrol vehicles, trucks and some were on motorcycles and immediately began to throw explosives and bombs,” said fisherman Audu Labbo.

Mr Labbo and other eyewitnesses confirmed that the troops from Nigeria and its neighbours Chad, Cameroon and Niger had fought until they ran out of ammunition.

Some soldiers removed their uniforms and threw away their rifles, he added.

A senior security officer in Borno state capital Maiduguri confirmed that the military base at Baga was under the control of the insurgents.

He said that the multinational force had run away because it received no reinforcements despite holding out for several hours.

There are fears that the extremists could use Baga as a base to attack Maiduguri, about 125 miles to the south-west.

Mr Labbo said that the insurgents’ bombs and grenades had set light to several buildings that burned to the ground — businesses, government offices, homes and part of the military base.

Boko Haram has been regionalising its conflict with recent attacks on Chadian villages and a military base.

Thousands of people have died and 1.6 million have become refugees because of the war.