Boko Haram has used kidnapped young women and girls on the front lines of its insurgency, according to a new report published on Monday, after a fresh abduction in Nigeria's far northeast.

Human Rights Watch made the claim as it outlined testimony from dozens of former hostages who documented physical and psychological abuse at the hands of the militants.

Around 30 adolescents -- some of them girls aged as young as 11 -- have been abducted in northeast Nigeria over the weekend by suspected Boko Haram rebels, a local village chief told reporters on Sunday.

"The insurgents... grabbed young people, boys and girls, from our region," said Alhaji Shettima Maina, who is in charge of the Mafa village around 50 kilometers (30 miles) east of the city of Maiduguri.

Cameroonian troops killed 39 Boko Haram fighters in clashes with the Islamists, who were carrying out three raids on Cameroon's territory, the defense ministry said Sunday.

Friday's fighting in the far north of Cameroon near Nigeria also claimed four civilian lives, the ministry said in a statement sent to AFP.

A source close to Nigerian President Goodluck Jonathan said on Thursday the leader of Africa's most populous country has decided to run for re-election in February.

Jonathan met with top officials from the ruling Peoples Democratic Party (PDP) and thanked them for their unanimous endorsement as the party's presidential candidate, the source said.

A deadly bombing in northern Nigeria and new details about kidnappings at the weekend blamed on Boko Haram cast further doubt Thursday on the government's claim that the Islamists have agreed to a truce.

As reports emerged that extremists seized dozens more women and girls from the remote northeast -- leaving a few dollars behind as a so-called 'bride price' -- fresh violence rocked the town of Azare in Bauchi state.

The Nigerian schoolgirls kidnapped by Boko Haram Islamists will face uncertainty if the extremists make good on an apparent pledge to free the teenagers they seized six months ago.

The government in Abuja claimed last Friday that it had secured a ceasefire deal and agreement on the hostages, raising hopes that the 219 teenagers held since April 14 would soon be coming home.

A bomb blast at a bus station in restive northern Nigeria's Bauchi state killed five people and injured 12 others, police said Thursday, confirming overnight witness reports.

"At about 9:45 pm (2045 GMT Wednesday) there was a bomb blast at (a) motor park roundabout in Azare town," police spokesman Mohammed Haruna said. "Five persons burnt beyond recognition were certified dead, while twelve others sustained various degrees of injury."

Nigeria's disputed claim to have brokered a ceasefire agreement with Boko Haram and release deal for more than 200 kidnapped schoolgirls was aimed at improving the country's tarnished reputation abroad and little to do with domestic politics, analysts say.

The surprise announcement on Friday created a sliver of hope that the brutal five-year Islamist uprising could be nearing an end and that the girls seized from the northeast town of Chibok of April 14 might rejoin their families.

Nigeria's government may have negotiated a supposed ceasefire with only one faction of Boko Haram, an influential regional group has said, as violence continued unabated in the far northeast.

The Borno Elders Forum, made up of retired senior civilian and military officials from the state, said attacks in recent days indicated that not all Boko Haram fighters were aware of the deal.

Relatives of Nigeria's kidnapped schoolgirls on Saturday dared voice cautious hope of seeing the teenagers finally freed after officials claimed to have reached a deal with Boko Haram militants.

Senior government and military officials on Friday said they had struck a ceasefire agreement with the Islamists ravaging the country's north.