BAGHDAD (AP) — Iraq's top Shiite cleric says the government must start hunting the "big heads" in an anti-corruption drive as the only way to achieve genuine reforms.

In a message delivered by a representative in a Friday sermon, Grand Ayatollah Ali al-Sistani, called for "convincing and assuring steps" as a proof of government seriousness in implementing its reform plan, which was announced and approved by parliament last month.

Al-Sistani's remarks came hours before weekly Friday rallies, which began last month, to protest shabby services, endemic corruption and sectarian politics. The graft is widely believed to be rampant, involving hundreds of millions of dollars in the 12 years since Saddam Hussein's regime was toppled.

Ahead of the protests, authorities closed all roads leading to Baghdad's Tahrir Square and deployed security forces.