By Anne Mireille Nzouankeu and Josiane Kouagheu

YAOUNDE (Reuters) - A suicide bomber belonging to Nigerian jihadist group Boko Haram killed at least 11 people when he blew himself up close to a mosque in Cameroon near the Nigerian border, military sources and local officials said on Thursday.

The attack occurred late on Wednesday and followed the breaking of the fast during the Muslim holy month of Ramadan.

"After the prayer, the faithful gathered under a tent in Djakana," said a local official. "A suicide bomber exploded and killed 11 people. Four others were injured."

A Cameroonian army officer said the bomber was a young boy.

Since a regional offensive last year drove the insurgents from most of their strongholds, Boko Haram has been waging a guerrilla-style campaign targeting civilians. In Cameroon, teenage girls have killed dozens in suicide bombings.

More than 15,000 people have been killed and 2 million displaced in Nigeria and neighboring Chad, Niger and Cameroon during Boko Haram's seven-year campaign to carve out an Islamic caliphate in northeast Nigeria.

The multinational joint task force, which has troops from all four Lake Chad countries, said on Wednesday it had swept through six villages and arrested 24 presumed accomplices of Boko Haram. In the operation, one soldier was killed and another injured by an improvised explosive device.

Boko Haram pledged its allegiance to Islamic State last year, although the practical extent of its links with the ultra-radical, Syria- and Iraq-based group is not known.

(Additional reporting by Boureima Balima in Niamey; Writing by Makini Brice; Editing by Ed Cropley/Mark Heinrich)