Somalia's al Qaeda-linked al Shabaab rebels said on Thursday they would increase their attacks against Uganda and Burundi days after the Islamist rebels joined forces with rival extremists Hizbul Islam.
"We, al Shabaab and Hizbul Islam have united and we warn Uganda and Burundi forces and their people that we shall redouble our attacks," sheikh Ali Mohamud Rage, al Shabaab's spokesman told a media conference in Mogadishu.
"We also inform our brothers in Afghanistan, Iraq, Nigeria and Uganda, that we have united in one name -- al Shabaab."
Kenya, Uganda and Tanzania have issued security alerts after a grenade exploded at a bus depot in Nairobi on Monday. Uganda said on Monday it had received intelligence reports than an al Qaeda-linked group was planning to hit the east African country during the festive season.