BAGHDAD — Suicide bombers killed 13 people in a pair of attacks yesterday around the Sunni Arab city of Ramadi in what local officials said was part of a power struggle between Al Qaeda and tribes that have broken with the terror network. In all, at least 68 people were killed or found dead nationwide yesterday, police said. They included the bullet-riddled bodies of 30 men found in Baghdad — the apparent victims of sectarian death squads.

All but two were found in Baghdad, including 17 in the Amil neighborhood where Sunni politicians have complained of renewed attacks by Shiite militiamen, said a police official who spoke on condition of anonymity because he was not supposed to release details.

Sunni complaints prompted the country’s Sunni vice president to threaten to leave the Shiite-dominated government unless key unspecified amendments to the constitution are not made by May 15.

The power struggle among the Sunnis, which surfaced last year, could prove decisive in the U.S. campaign to win over significant portions of the Sunni community, which has formed the bedrock of the insurgency.