Al-Sadr's Iranian mentor withdraws his support

Yet Iran's position on al-Sadr is unclear. It has formally said it wants to see stability in Iraq and does not support any militia force.

Iranian political analysts, however, say hard-liners in Iran may secretly want to stir the violence in Iraq to prevent the formation of a powerful Shiite center in Najaf, which could overshadow the religious leadership role of Qum.

"The news had such a negative impact in Qum that Ayatollah Haeri was forced to withdraw his support for Mr. Sadr," Qabel said.