MAIDUGURI (Nigeria), May 17: Nigerian forces used jets and attack helicopters to bombard militant camps in the northeast on Friday, their biggest offensive since Boko Haram began an insurgency almost four years ago to try creating a breakaway Islamic state.

A military source said at least 30 militants had been killed in the operation, which the defence headquarters spokesman said included the Sambisa game reserve in Borno state, centre of the uprising and heart of a medieval Islamic empire.

“It is not just Sambisa, every camp is under attack,” the spokesman, Brigadier-General Chris Olukolade, said by telephone.

“But we have not done the mopping up operations on the ground to determine the numbers killed.”

Nigerian forces are trying to regain territory controlled by well-armed Boko Haram militants in remote northeastern stronghold states of Borno, Yobe and Adamawa, put under a state of emergency by President Goodluck Jonathan on Tuesday.

The Muslim militants, seen as the main security threat to Africa’s top oil producer, have been staging bolder attacks since last month, including one on the town of Bama that left 55 dead.

Nigerian authorities fear they are creating an enclave in remote border areas, as Al Qaeda linked militants did in the deserts of Mali before the French forced them out in January.

More troops arrived in the Borno state capital Maiduguri on Friday, witnesses said.

“I saw more than 20 trucks loaded with soldiers fully kitted for battle towards Marte. I wish them luck in ending this BH (Boko Haram) madness,” resident Ahmed Ibrahim said.

A day earlier, 11 trucks of police trained in counter-insurgency had arrived in Maiduguri, security officials said. Mobile phone connections to Borno and Yobe states were cut.

In some parts of Maiduguri, and in Yola, the capital of Adamawa state, life was slowly returning, with traffic back on the roads and shops re-opening, as many of the military operations take place in remote rural areas. Roads out of the city to such areas were sealed off by soldiers.

Thousands of troops are involved in the offensive — the precise number is a secret — an answer to critics who accuse Mr Jonathan, a southern Christian, of underestimating the severity of the crisis in the largely Muslim north.—Reuters