MOGADISHU, Somalia — The militant group al-Shabab said the man who carried out a suicide bomb attack on a base in Mogadishu this week was a Somali-American, and an official said Thursday that separate clashes with militants in Somalia’s capital left at least 17 civilians dead.

Al-Shabab said on its website Thursday that a 25-year-old man named Abdullahi Ahmed was the suicide bomber who attacked an African Union peacekeeping base in Mogadishu, Somalia’s capital, on Monday, killing two AU troops and one government soldier.

Ahmed was said to have moved to Somalia from Minnesota two years ago.

The Internet report purported to quote Ahmed before his death saying that he wanted to carry out the attack because of abuses by Christians of Muslim countries.

If the report is confirmed, Ahmed would become at least the third Somali-American to have carried out a suicide bombing in Somalia.

Somali Islamic insurgents — some of whom have links to al-Qaida — have been recruiting young Somali men in America and other countries amid fears that insurgents could use the men to attack foreign targets.

The first known American suicide bomber in Somalia, Shirwa Ahmed from Minneapolis, blew himself up in October 2008 in the northern breakaway republic of Somaliland as part of a series of coordinated explosions that killed 21 people.

In September 2009, insurgents including an 18-year-old from Seattle, drove two stolen U.N. cars into an AU base and detonated them. Twenty-one people were killed.

At least 20 Somali-Americans are believed to have joined al-Shabab. U.S. authorities have warned that a Somali-American who seeks training from al-Shabab could return to the United States to carry out an attack.

Somali troops backed by African Union peacekeepers on Thursday continued to attempt to oust militants from Mogadishu’s main Bakara market.

Mogadishu ambulance chief Ali Muse said medical officials collected 17 dead bodies and 40 people who were wounded in mortar exchanges between the two sides.

Bakara market is a top revenue stream for al-Shabab, which taxes the market’s merchants. Bakara — where anything from infant formula to flat-screen TVs are available — is the lynchpin of Mogadishu commerce, making it valuable ground for both sides.