Niger army fights Boko Haram for Lake Chad island after attack

Niger's army is fighting to recapture an island in Lake Chad after it was seized by hundreds of Boko Haram militants aboard motorized canoes, army sources said on Sunday.

Boko Haram, hardline Islamists who want to establish a caliphate in the region, attacked the island of Karamga at dawn on Saturday, their second attempt to capture it since February, army and government sources said.

Lake Chad's islands, which lie in dense swampland, are an ideal base for mounting surprise attacks on the countries bordering the lake: Chad, Cameroon, Niger and Nigeria.

"There were many (Niger soldiers) dead on Saturday, considerably more than in the first attack," said one of the army sources, referring to a battle in February in which seven Niger soldiers died.

A second army source said a counter-attack to clear the island of militants was ongoing.

Since February, Nigerian forces backed by neighbors Chad, Niger and Cameroon have won back vast swathes of territory from Boko Haram, which previously controlled an area the size of Belgium.

The militants, who have killed thousands of people in their six-year insurgency, are thought to be largely hemmed in within north Nigeria's vast Sambisa Forest where the Nigeria military says it is advancing.

However, on Friday suspected Boko Haram militants crossed over from Cameroon and forced Nigerian troops out of the border town of Marte, one soldier told Reuters, indicating the group still has a reach beyond Sambisa.

The island of Karamga is hundreds of kilometers away, suggesting that there is at least one Boko Haram cell further north.

Niger suffered a wave of attacks and suicide bombs in its southern border region of Diffa in February and March, prompting the government to declare a state of emergency there.

The last known attack was on the town of Bosso on March 30, although there were no casualties on Niger's side.