An al Qaeda-linked Somali militant group says it was behind twin deadly bombings in Uganda that killed 74 people watching the World Cup final on TV.

Leaders for the group, called al-Shabab, said their militants would carry out further attacks "against our enemy" wherever they are.

"No one will deter us from performing our Islamic duty," said spokesman Sheik Ali Mohamud Rage, in Mogadishu, Somalia.

Ugandan officials had said earlier they suspected the Somali group was involved. The blasts had come two days after a commander with al-Shabab called for militants to attack sites in Uganda and Burundi, two countries that contribute troops to the African Union peacekeeping force in Somalia.

As well, one of the targets of Sunday's bombings was an Ethiopian restaurant -- a nation despised by al-Shabab.

Al-Shabab has long threatened to attack outside of Somalia's borders, but this is the first time the group has done so.

The Sunday bombings killed at least 74 people who had gathered to watch the World Cup; another 60 were wounded.

The blasts happened at a rugby club and an Ethiopian restaurant in the Ugandan capital of Kampala, and appear to have been planned to go off in the middle of the match. Ugandan government spokesman Fred Opolot said Monday there were indications that two suicide bombers took part in the attacks.

The attack on the rugby club, where crowds had gathered outside to watch a large-screen TV, left 49 dead. Fifteen others were killed in the restaurant explosion.

Later, al-Shabab commander Sheik Yusuf Sheik Issa told The Associated Press that he was happy with the attacks.

"Uganda is one of our enemies. Whatever makes them cry, makes us happy. May Allah's anger be upon those who are against us," Sheik said.

A California-based aid group 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 President Yoweri Museveni toured the blast sites Monday and said the terrorists behind the bombings should fight soldiers, not "people who are just enjoying themselves."

"We shall go for them wherever they are coming from," Museveni said. "We will look for them and get them as we always do."

Officials said the attacks will not affect the African Union summit being held in Uganda from July 19-27. Many African leaders are expected to attend.

"The summit will go on. The AU and African countries have the resolve to fight terrorism with the international community," said Ramtane Lamamra, the AU's peace and security commissioner.

Al-Shabab's fighters have carried out multiple suicide bombings in Somalia.

With reports from the Associated Press