KAMPALA, Uganda— An al-Qaida-linked Somali militant group suspected in twin bombings in Uganda's capital that killed 64 people watching the World Cup final endorsed the attacks today but stopped short of claiming responsibility, as Uganda's president vowed to hunt down those responsible.

The blasts came two days after a commander with the Somali group, al-Shabab, called for militants to attack sites in Uganda and Burundi, two nations that contribute troops to the African Union peacekeeping force in Somalia.

The attacks also raise concerns about the capabilities of al-Shabab, which the U.S. State Department has declared a terrorist organization. If confirmed that the group carried out the attacks, it would be the first time al-Shabab has struck outside Somalia. In Mogadishu, Somalia, Sheik Yusuf Sheik Issa, an al-Shabab commander, told The Associated Press early today that he was happy with the attacks in Uganda but refused to confirm or deny that al-Shabab was responsible.

"Uganda is one of our enemies. Whatever makes them cry, makes us happy," Sheik said.

Kampala's police chief, Kale Kaihura, said he believed al-Shabab could be responsible.

A California-based aid group, meanwhile, said one of its American workers was among the dead. Police said Ethiopian, Indian and Congolese nationals were also among those killed and wounded, police said.

Ugandan government spokesman Fred Opolot said today there were indications that two suicide bombers took part in the late Sunday attacks, which left nearly 60 others wounded.

Blood was splattered on the floor among overturned chairs at the scenes of the blasts, which went off as people watched the game between Spain and the Netherlands. The attack on the rugby club, where crowds sat outside watching a large-screen TV, left 49 dead, police said. Fifteen others were killed in the restaurant explosion.