"We are surprised by the silence in Najaf where the highest Shiite religious authority is based," Sheikh Sattar Battat said, referring to Sistani.

"For 50 days Sadr City is being bombed ... Children, women and old people are being killed by all kinds of US weapons, and Najaf remains silent," he told the faithful at the weekly Friday prayers in Sadr City, Sadr's stronghold.

Battat said the Sadr movement has not seen any "reaction or fatwa (religious decree) from Najaf" criticising the government assault on Shiite fighters in Sadr City.

"For us this means that Najaf accepts the massacre in Sadr City," a sprawling slum district that has been the site of fierce clashes between US forces and Sadr's Mahdi Army militia since late March.

The clashes broke out after Prime Minister Nuri al-Maliki ordered a crackdown on Shiite militiamen on March 25 in the southern city of Basra.

Sadr's Mahdi Army militia offered stiff resistance. The clashes then spread to other areas, particularly to Sadr City, where hundreds have been killed.

Shiite clerics, including Sistani, have remained silent despite the high casualties, suggesting that they were backing the government's crackdown on the militants.

On Friday, Sheikh Battat also launched a fresh tirade against Maliki, who he said was "murdering people with the help of a foreign state."

"What the government is doing is a crime against the people."

© 2008 Agence France-Presse