Sectarian violence in Iraq spread to its holiest Shiite city yesterday when a suicide bomber aiming for pilgrims in Najaf killed at least 35 people and wounded 122.

The bomber blew up explosives wrapped around his body while being patted down by a policeman at a checkpoint in front of the Imam Ali mosque, which contains the tomb of the Prophet Muhammad’s cousin and son-in-law, Ali.

The row of shops and market stalls that sprawls in front of the shrine’s entrance, called the Grand Market, is normally thronged with hundreds of pilgrims. After the explosion, boxes of perfume bottles, sandals, and worry beads littered the street. Volunteers picked up human remains and washed away blood.

The shrine, which is the most revered in Shiite Islam, was not damaged. Hospital sources said of those killed, 22 were men, including five policemen. Four Iranian pilgrims were hurt, and so were children.

Television footage showed the body of a child being laid beside other bloodied corpses beside a hospital. The dead were marked and numbered with white labels on their foreheads for identification.

Iraq’s Shiite prime minister, Nouri al-Maliki, called the bombing a “barbarous massacre conducted by Takfiris [Sunni extremists] and Saddamists, who are seeking to inflame sectarian” tensions.

In an Internet posting, responsibility was claimed by a Sunni insurgent group, Jamaat Jund al-Sahaba. The group warned Shiites to stop killing unarmed Sunnis or, “otherwise, wait for such operations that will shake your regions like earthquakes.”

Najaf has been relatively stable because its religious significance means that it is heavily guarded by police, soldiers, and militiamen. However, in December 2004, the Imam Ali shrine was attacked by a suicide car bomber, who killed 52 people.

Eighteen people died in violence elsewhere in Iraq yesterday, most of them in Baghdad.