A suicide bomber who killed 24 people last week at a university graduation ceremony in Somalia"s capital was a Danish citizen of Somali descent, a top Somali government official told The Associated Press Thursday. Information Minister Dahir Gelle said that the bomber was identified by his father after a photo of his body was released. Gelle said more tests would be carried out. No confirmation was immediately available from officials at Denmark"s embassy in Nairobi. The bombing killed three government ministers and 21 others during a graduation ceremony of medical students last Thursday. The killing of doctors desperately needed in the war-ravaged country provoked the first known protests against the insurgent group al-Shabab in Somalia. The U.S. State Department says some al-Shabab leaders have links to al-Qaida. DNA tests have shown that at least one suicide bomber in Somalia was an American citizen, and results are awaited on a possible second American-Somali suicide bomber. American officials say around 20 young Americans of Somali descent have returned to Somalia and officials are worried that one of them may return to launch an attack on American soil. Suicide bombers were virtually unknown in Somalia until 2007 but are becoming increasingly common. Gelle said many of the attacks are carried out by an influx of young Somalis who have grown up abroad and may hold foreign citizenship. «They are more committed, they have got knowledge, they are well-educated,» he said, listing the reasons why the Somali returnees were dangerous. Many of the Somalis who traveled overseas had difficulty fitting into their adopted societies, he said, and their feelings of alienation and poor knowledge of the Quran made them particularly vulnerable to recruitment by jihadists. «We"re afraid that this Danish-Somali has been brainwashed right here in Denmark,» Somalia"s Environmental Minister Buri Hamza said in a live television interview with Denmark"s TV2 channel from the climate summit in Copenhagen. «He left Denmark just about, I understand, 18 months ago, and he was really new in Somalia. The actual brainwashing, indoctrination must have taken place outside Somalia.» According to Denmark"s Politiken newspaper, the man had come to Denmark at the age of 5 and was in his late 20s. Mohammed Gelle, chairman of the Danish-Somali Association, said the man"s family had no knowledge of his plans. «His family is worried that he moved to Somalia with his wife and daughter. The family opposed it but he is a grown-up man,» Mohammed Gelle said. One of the suicide bombers who attacked an African Union peacekeeping base in September was able to get past the guards partly because he spoke fluent English with an American accent and was driving a stolen U.N. vehicle, Information Minister Dahir Gelle said. «It would take the insurgents years to train someone to learn English to that level,» he said. «Now they are coming over to volunteer.» Somalia has not had a functioning government since 1991, when warlords overthrew a socialist dictator and then turned on each other. The embattled U.N.-backed government is fighting an Islamist insurgency that is increasingly using tactics honed in Iraq and Afghanistan.