Cameroon's army has freed 24 of around 80 hostages kidnapped in a raid by Boko Haram Islamist fighters based in neighbouring Nigeria.

Many children were among those abducted in the attack, which left three people dead. However, a defence ministry spokesman, Colonel Didier Badjeck, said: "The Cameroon army was able to free about 24 hostages taken yesterday by Boko Haram in the far north. They were freed as defence forces pursued the attackers who were heading back to Nigeria."

Most of those kidnapped - around 50 - were children aged between 10 and 15, with 30 adults, according to a senior army officer.

Boko Haram has brought territory the size of Belgium under its control in northern Nigeria and the Nigerian army has been unable to deal with its depredations. The group, which has killed thousands and kidnapped hundreds in its bid to carve out an Islamic state, has also targeted Cameroon and Niger over the past year as it seeks to expand its zone of operations.

Sunday's kidnappings, among the largest abductions on Cameroonian soil, came as neighbouring Chad deployed troops to support Cameroon's forces in the area.

The army officer said that the early-morning attack had targeted the village of Mabass and other villages along the porous border. Soldiers intervened and exchanged fire with the raiders for around two hours, he added.

Government spokesman Issa Tchiroma confirmed the attack, in which he said three people had been killed, as well as the kidnappings. He was not able to say with certainty how many people had been taken in the raid.

"There was a Boko Haram attack on several localities in the Far North region. The assailants burnt down about 80 homes and kidnapped several inhabitants including women and very young children," he said.

In an attack that gained worldwide attention last year, its fighters kidnapped around 200 schoolgirls from the town of Chibok, in northeastern Nigeria.

It has stepped up attacks in the region as Africa's biggest economy prepares for a February 14 presidential election.

In a video posted online this month, a man claiming to be Boko Haram leader Abubakar Shekau threatened to step up violence in neighbouring Cameroon unless it scraps its constitution and embraces Islam.

Faced with increased violence along the border, Yaounde has deployed thousands of additional troops, including elite soldiers, to the area.

A convoy of troops from Chad arrived in Maroua, the main town in Cameroon's Far-North Region, to support the fight against Boko Haram, late on Saturday, Colonel Badjeck said on Sunday.

Chad has a reputation as one of the region's best militaries and helped French forces drive al Qaeda-linked Islamists from northern Mali in 2013. Government officials in N'Djamena say the deployment to Cameroon includes around 2,000 soldiers, armoured vehicles and attack helicopters.

Ghana's President John Mahama, who currently heads West African bloc ECOWAS, said on Friday that regional leaders will seek approval from the African Union next week to create a new force to fight Boko Haram.