"Our intelligence so far confirms that they were suicide attacks," Maj. Gen. Kale Kayihura, Uganda's national police chief, told reporters. The international police organization Interpol was distributing the photo reconstructions in an attempt to identify the attackers, Kayihura said.

Interpol and the FBI have helped confirm the attacks were suicide bombings, he said,adding that investigators suspect that two severed heads found parts attached are those of the bombers.

The Somali Islamist insurgent movement Al-Shabaab has claimed responsibility for the attacks, calling them retaliation for Ugandan participation in an African Union (AU) peacekeeping mission in Somalia. Uganda is hosting an African Union summit this week, and Kayihura said the Ugandan government has urged the organization for the authority to hunt down Al-Shabaab members "in their bases which are known to us."

The AU peacekeeping mission AMISOM has about 5,200 troops -- 3,200 from Uganda, the rest from Burundi. The troops are there to support the U.N.-backed transitional government in Somalia, which has been without an effective central government since 1991.