Both peacekeepers and insurgents say fighting in Somalia is set to increase during the Muslim holy month of Ramadan.

A spokesman for the African Union peacekeeping force in Mogadishu, Major Ba-Hoku Barigye, says troops are preparing for a surge in attacks from militants over the next thirty days.

The prediction comes as authorities in Kenya say they have arrested dozens of non-Somalis over the last two months suspected of attempting to cross the border to join insurgent fighters.

Hizbul Islam, one of the groups fighting AU forces and soldiers from the Somali transitional government, has vowed to step up its assaults during the holy month.

A militia group fighting the insurgents, Ahlu-Summa Wal-Jama, says it will increase its own attacks.

Ramadan begins Wednesday for Somalia's mostly Sunni Muslims. Observers refrain from eating, drinking and sexual relations between daybreak and sunset.