Nigeria’s electoral commission is to postpone presidential and legislative elections for six weeks to give a new multinational force time to secure north-eastern areas under the sway of Boko Haram, an official has said.

Millions could be disenfranchised if the voting went ahead on February 14th while the Islamic extremists hold a large area of the north east and continue the violence that has driven 1.5 million people from their homes.

A major offensive with planes and ground troops from Chad and Nigeria has forced the insurgents from a dozen towns and villages in the past 10 days, and greater military strikes by more countries are planned.

The official said the Independent National Electoral Commission will announce the postponement at a news conference. Officials in President Goodluck Jonathan’s administration had been calling for a postponement, which is opposed by an opposition coalition fielding his chief rival, former military dictator Muhammadu Buhari.

Supporters of both sides are threatening violence if their candidate does not win. Some 800 people were killed in riots in the mainly Muslim north after Mr Buhari, a Muslim, lost 2011 elections to Mr Jonathan, a Christian from the south.

A postponement will give electoral officials more time to deliver 30 million voter cards. The commission had said the non-delivery of cards to nearly half of the 68.8 million registered voters was not a good reason to delay the vote.

Early on Saturday, officials in Niger said more than 100 Boko Haram fighters had been killed by soldiers responding to attacks on two towns near the border with Nigeria.

Defence minister Karidjo Mahamadou said four soldiers died and 17 were wounded in fighting in the towns of Bosso and Diffa.

He said two soldiers were missing and a civilian was also killed. Niger’s army received support from Chad as it worked to repel Boko Haram’s assault.