MUQDADIYA, Iraq A suicide bomber blew himself up at a mourning ceremony inside a Shi'ite mosque in Iraq late on Monday, killing at least 22 people, police said.
The explosion brought down the ceiling of the mosque in the town of Muqdadiya, 80 km (50 miles) northeast of the capital Baghdad, crushing Shi'ites who were marking the death of a police officer killed in a recent roadside bombing.
Police said the death toll could rise because people remained trapped beneath the rubble.
The violence is part of a sustained campaign of militant attacks since the start of the year that has prompted warnings of wider conflict in a country where ethnic Kurds, Shi'ite and Sunni Muslims have yet to find a stable power-sharing compromise.
A separate suicide bombing in a coffee shop in a Shi'ite district of the city of Baquba, about 50 km northeast of Baghdad, brought Monday's death toll to 27.
No group immediately claimed responsibility for the attacks, but suicide bombings are the trademark of al Qaeda's local affiliate, the Islamic State of Iraq, which security experts say has regained strength in recent months.
Insurgents have been recruiting from Iraq's Sunni minority, which resents Shi'ite domination since the U.S.-led invasion that toppled Saddam Hussein in 2003.
Sectarian tensions have been inflamed by the civil war in neighboring Syria, which is fast spreading into a region-wide proxy war, drawing in Shi'ite and Sunni fighters from Iraq and beyond to fight on opposite sides of the conflict.
Highlighting the risks of spillover, security forces on Monday destroyed an insurgent camp near the Iraqi town of Baaj, around 30 km from the Syrian border, killing 10 gunmen who were not of Iraqi origin, police said.
Three members of the security forces also died in the clashes.
The number of people killed in militant attacks across Iraq reached 761 in June, the United Nations said on Monday, still well below the height of bloodletting in 2006-07 when monthly death tolls sometimes topped 3,000.
Iraqi military forces are now better equipped and trained, but lack the comprehensive intelligence resources and air cover capability to track insurgents that they enjoyed before U.S. troops withdrew in December 2011.
(Reporting by a Reuters reporter in Diyala and Zaid al-Sinjary in Mosul and Raheem Salman in Baghdad; Writing by Isabel Coles; Editing by Andrew Heavens)