Kaduna, Nigeria - The Nigerian military arrested 120 suspected Boko Haram militants on Monday in Borno State, in a sweep to curb the insurgency in the country's north-east, the army said.

The extremists were arrested during a funeral rite in the Borno capital, Maiduguri, for one of their commanders, who had “died in an encounter with special forces the previous day”, the army statement said.

The Nigerian military last week launched an offensive against the extremists in Yobe, Borno and Adamawa states, after President Goodluck Jonathan declared a state of emergency in those areas on May 14.

The Islamist sect has been waging an insurgency against the government and Western culture and lifestyle since 2009 in Africa's most populous country.

The suspects were being interrogated by the military, which blocked insurgents from fleeing toward neighbouring Chad and Niger.

The army said it had secured five areas in the affected states “after destroying all the terrorists camps” there.

Earlier on Monday, the lockdown in the state of Yobe was modified from a 24-hour curfew since Friday to a curfew from 6pm to 6am.

Yobe Governor Abdullahi Bego called on residents to co-operate with security agencies to dislodge Boko Haram members from their hideouts.

Fighter jets have pounded the training and recruitment camps of the insurgents near the borders with Niger, Chad and Cameroon.

Fourteen rebels and three government soldiers were killed in the battles in unspecified locations, military spokesman Brigadier General Chris Olukolade said earlier Monday. He said 20 fleeing insurgents were arrested.

At least 2 000 soldiers reportedly deployed last week in the three states, and 1 000 more were expected to arrive at the Yola army base in Adamawa state.

An estimated 2 000 people have fled the border towns into neighbouring Niger to avoid being caught up in the clashes, the BBC's Hausa service reported.

According to the New York-based Human Rights Watch, attacks by Boko Haram or its splinter groups and extrajudicial killings by security forces have left more than 3 600 people dead since 2009. - Sapa-dpa