Baghdad ? Iraqi troops arrested the son of a leading Sunni politician and dozens of his associates after a car bomb was discovered near his compound and keys to the vehicle were found on one of his bodyguards, U.S. and Iraqi officials said Friday.

Five U.S. soldiers and an Iraqi civilian were injured when they detonated the car bomb near the compound of Adnan al-Dulaimi, leader of the biggest Sunni bloc in parliament, the U.S. military said.

The arrests threaten to inflame sectarian tensions at a time when U.S. officials are pushing Iraqi politicians to take advantage of a decline in violence to forge power-sharing agreements among Sunnis, Shiites and Kurds.

Al-Dulaimi’s bloc, the Iraqi Accordance Front, accused Shiite-dominated security forces of “creating and marketing this crisis” to undermine U.S. efforts to organize Sunni tribes against al-Qaida.