AFP/Yaoundé

At least 30 people were killed in two suicide bombings in northern Cameroon on Thursday, the latest violence to hit the area since dozens died in attacks in July blamed on the Boko Haram Islamist group.

The attacks were launched three days after Boko Haram gunmen on horseback killed dozens of people in a village across the border in northeast Nigeria's Borno state.

The fresh violence comes even as Nigerian President Muhammadu Buhari, who marks 100 days in office on Saturday, has intensified the battle against Boko Haram.

The Nigerian army said on Thursday it had reinstated about 3,000 soldiers who were dismissed for alleged indiscipline in the battle against the insurgents.

Attacks by Boko Haram, which wants to impose a strict Islamic system in northern Nigeria, have killed at least 15,000 people and displaced 1.5mn since 2009.

Military and police sources in Cameroon said the first suicide bombing took place shortly before noon in the marketplace of Kerawa, a city on the border with Nigeria.

It was followed by a second attack about 200 metres from a military camp, said a police officer who asked not to be identified.

At least 30 people were killed, the sources said, but there was no indication of the number of wounded.

Some 50 people were killed in July in the same region in five suicide attacks blamed on Boko Haram.

Cameroon is part of a five-nation coalition fighting Boko Haram with Nigeria, Chad, Niger and Benin.

Cameroon's far north region bordering Nigeria and Chad for the past two years has seen frequent Boko Haram raids, kidnappings and, more recently, suicide attacks.

Witnesses in the village of Fatawe in Nigeria's Borno state told AFP that Boko Haram militants on Monday rounded up residents, tying their hands behind their backs then slitting their throats.

"They killed several dozens but I can't give a precise number because we have yet to go back and take a headcount of the dead," said Amodu Kadir, a village resident who fled to Mubi village in neighbouring Adamawa state.

Kadir, whose father was among the victims, said the "macabre sight sent the terrified crowd fleeing in all directions in a frenzied effort to escape.

"But the attackers pursued us on their horses, shooting and trampling to death their victims," he said.