ABUJA: Nigerian police have arrested most of the suspects in bombings that killed hundreds of people in the past two years, President Goodluck Jonathan said.

An Islamist insurgency in Nigeria's impoverished north has intensified since Jonathan, a southern Christian, came to office in 2010. It represents the most serious threat to Africa's most populous nation.

At least 32 people have died in the past week in gun and bomb attacks in the northeast, where Islamist group Boko Haram is strongest, but Jonathan said the violence was temporary.

"Most of these terror suspects have been arrested," he said at a New Year's Day church service in the capital Abuja on Tuesday.

"These people involved in some of these crimes - like bombing of the Catholic Church in Niger state, bombing of the United Nations building, bombing of the police headquarters - have been arrested. These are momentary challenges."

He did not say who was detained and when, or whether they would face trial. The attacks he listed all took place in 2011.

Jonathan has said several times that the authorities are winning the battle against Boko Haram, but officials have given few details on how they are clamping down on its activities.

A ramp-up in security across northern towns and cities ensured Christmas violence was more muted than in the previous two years, when dozens were killed in church bombings.

Boko Haram, which is loosely based on the Afghan Taliban, is trying to impose Islamic law on the country of more than 160 million, which is split roughly equally between Christians and Muslims.

Jonathan has been criticised for using solely a military approach to the unrest, pushing young Muslims disillusioned with his government into joining Boko Haram.