Nairobi: Boko Haram terrorists killed at least 100 civilians in the northern Cameroonian city of Fotokol, on the border with Nigeria, in response to a joint counter-terrorism operation by the armies of Chad and Cameroon.

The militant jihadis also burned down houses and mosques in the city, according to representatives of local organisations whose accounts were cited in Thursday`s edition of the daily L`oeil du Sahel.

"Boko Haram entered the city of Fotokol this morning and killed more than 100 people in the mosque and in their homes," said one of the area`s residents after the terrorist group killed his sons.

Cameroon Information Minister Issa Tchiroma said the attack on Fotokol also resulted in the death of at least 50 terrorist, while six Cameroonian soldiers were killed as well.

The Fotokol raid was an act of retaliation for the operation that allowed the joint forces to regain control of the Nigerian city of Gamboru, where least 250 members of the terrorist group were killed in two days of fighting along the border between Cameroon and Nigeria.

It was the first major regional offensive against Boko Haram, as the group has mainly concentrated its attacks on northern Nigeria, especially in the states of Borno, Yobe and Adamawa, where it has killed nearly 1,000 people and kidnapped hundreds more in recent years.

The governments of Chad and Cameroon have confirmed that more than 250 members of Boko Haram have been killed in the last two days, according to Nigerian newspaper The Guardian.

In Chad, public television reported Wednesday that Chadian troops managed to kill at least 200 extremists to completely destroy Boko Haram bases in the cities of Gamboru and Ngala in northern Nigeria, while nine Chadian soldiers were killed in action on Nigerian soil.

Last week, the African Union (AU), authorised the deployment of 7,500 soldiers from regional forces to fight the terrorists, who have been trying for the past five years to impose an Islamist state in northern Nigeria.

Chadian forces, which have one of the strongest military capabilities in the region, have carried out airstrikes against the rebels` locations in recent days.

Chad also sent aircraft from their bases in the capital on reconnaissance missions along the border with Nigeria.

With the approach of the Nigerian presidential elections set for Feb 14, Boko Haram has intensified its attacks in that country`s northeastern regions and along its borders.