BAGHDAD, Iraq — Iraqi forces captured a key al-Qaida suspect wanted in the bombing of a Shiite shrine, but the mastermind of the attack that brought the country to the brink of civil war was still at large, a top security official said today.

Yousri Fakher Mohammed Ali, a Tunisian also known as Abu Qudama, was captured after being seriously wounded in a clash with security forces north of Baghdad a few days ago in which 15 other foreign fighters were killed, National Security Adviser Mouwafak al-Rubaie said.

He also identified the fugitive ringleader in the operation as an Iraqi named Haitham Sabah Shaker Mohammed al-Badri, the head of a gang that included two other Iraqis, four Saudis and Abu Qudama. He said the gang planted bombs in the 1,200-year-old Askariya mosque that exploded on Feb. 22 and obliterated its glistening golden dome, an addition completed in 1905.

A spasm of sectarian killing and revenge attacks on Sunni and Shiite mosques after the bombing of the revered shrine in Samarra, 60 miles north of Baghdad, took the country to the brink of civil war.

Since then, more than 20,000 families were displaced, hundreds of civilians killed, and dozens of Sunni and Shiite mosques damaged or destroyed.

The mosque attack was staged "in order to ignite sectarian strife among the Iraqi people," al-Rubaie said.

The announcement came as the Iraqi government struggled to contain rampant ethnic and sectarian violence in the country and days after Iraq's Shiite Prime Minister Nouri al-Maliki unveiled a 24-point national reconciliation plan aimed at bringing Sunni Arab insurgents into the political process.

In other news, a suicide car bomber blew up himself near a Sunni mosque in a market south of the northeastern city of Baqouba, killing one person and wounding 12, police said.