The attack was one of several to strike predominantly Sunni Arab northern Iraq, beset by growing instability in recent months as anti-government protests have combined with spillover from neighbouring Syria's years-long civil war to give militant groups increased room to manoeuvre.
The bomber blew himself in the town of Baashiqah, just outside the main northern city of Mosul, killing 26 people and wounding 46, according to Sheeth Abed, a doctor at the city's hospital.
The 30,000-strong Shabak community mostly lives near the Turkish border.
They speak a distinct language and largely follow a faith that is a blend of Shiite Islam and local beliefs, and are frequently targeted in attacks by Sunni militants linked to Al-Qaeda.
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Also today, two other attacks in Nineveh province, of which Mosul is the capital, left a policeman dead and three others wounded.
An explosion in Dujail, which also lies north of Baghdad, killed two others.
The attacks come amid a surge in nationwide violence that has left more than 4,000 people dead so far this year and sparked concerns Iraq is slipping back into the all-out sectarian war that plagued it in 2006 and 2007.
Authorities insist a weeks-long campaign targeting militants is yielding results, but the government has faced criticism for not doing more to defuse anger in the Sunni Arab community over alleged ill-treatment at the hands of the Shiite-led authorities.
Analysts and diplomats say militant groups exploit that on the ground to recruit and carry out attacks.