Najaf, Iraq: A local representative of Grand Ayatollah Ali Al Sistani, the reclusive spiritual leader of Iraq's Shiite majority, was gunned down outside his home, Sistani's office and police said on Wednesday.

Raheem Al Hasnawi, who represented Sistani in the town of Al Mishkhab, 40 km north of the holy Shiite city of Najaf, was killed late on Tuesday, they said.

A spokesman for Sistani's office said three gunmen riding in a car shot Hasnawi outside his home in Al Mishkhab.

"He was killed immediately," the spokesman said.

An Iraqi security source said Hasnawi was shot in the head and chest. There was no immediate indication about who was responsible for the killing.

Sistani is the sponsor of the ruling United Alliance bloc to which Prime Minister Nuri Al Maliki and other Shi'ite political leaders belong.

He is acknowledged as the patron of a delicately structured Shi'ite political movement which also includes anti-American cleric Moqtada Al Sadr's political movement.