"I am optimistic that these numbers will be raised now - especially now - because these people have provoked the world more than before. And I can assure you they have invited a lot of problems for themselves," Museveni told journalists in Uganda.

He said he wanted to send up to 20,000 troops to Somalia to "eliminate" the hardline Islamist group.

Al-Shabab has claimed responsibility for the twin attacks on people watching the World Cup final because Ugandan troops are supporting the Somali government. Museveni said other countries would now send troops to Mogadishu, in a BBC report.

"We were just in Mogadishu to guard the airport and the presidential palace - that was all," he said. "We are going to go on the offensive and go for all who did this in all areas, starting here."