BAGHDAD, June 30 (IslamOnline.net & News Agencies) - Several Iraqis were killed in an explosion at an ammunition dump over the weekend in Haditha, 260 kilometers (160 miles) northwest of Baghdad.

"There was an explosion and then a fire at an ammunition dump in the town of Haditha," a U.S. military official told Agence France-Presse (AFP) on Monday.

"There were several casualties," he said, without elaborating.

U.S. Sergeant First Class Patrick Compton, meanwhile, told AFP that the casualties were all Iraqis.

"There are no U.S. casualties," he said.

Al-Jazeera correspondent reported that more then 90 Iraqis were killed and dozens injured in the blast.

It was not known if the blast was the result of an accident, or the latest in a string of attacks on the U.S. forces.

Meanwhile, U.S. occupation forces in Iraq on Monday arrested the U.S.-appointed governor in the southern city of Najaf on charges of kidnapping and theft, in an embarrassing blow to their attempts to control the country.

The arrest came as a top Iraqi Shiite religious authority considered a "moderate" slammed the U.S.-led forces' plans to appoint a body to draft a new constitution, saying the occupying forces were not authorized to do so.

The twin setbacks overshadowed the launch of a major sweep north of Baghdad, with U.S. forces vowing to crush the Iraqi resistance they blame for a string of attacks on occupation forces.

Senior "coalition" spokesman Charles Heatley said the governor, Abu Haidar Abdul Munim, had been removed from office and replaced by his deputy.

"He faces a multitude of charges which include: kidnapping and holding hostages; pressurizing government employees to perform financial crimes; attacking a bank official and stealing funds."

U.S. civil administrator Paul Bremer "was particularly distressed that this official was misusing his public office to commit crimes of this sort," Heatley said. "We will make mistakes ... We clearly made a mistake with this chap."

The embarrassment was compounded by an edict from Grand Ayatollah Ali al-Sistani, a top Shiite authority, who said coalition plans to draft a new Iraqi constitution would have to be preceded by general elections.

"The (occupation) authorities are not entitled to name the members of the assembly charged with drafting the constitution," Sistani said, labeling U.S. plans to appoint a committee to draft the text "unacceptable".

Sistani, whose rulings are widely obeyed by Iraq's majority Shiite community, called for elections to be held "so that every eligible Iraqi can elect his representatives to the assembly that will draft the constitution."

The U.S.-led occupation has said it does not intend to hold a general election for at least one year, while it attempts to wipe out resistance, restore order and get the country's stalled economy back on track.

U.S. troops patrolling the holy Shiite Muslim city of Najaf have earlier heaped praise on Ayatollah Ali al-Sistani for having used his community standing to foster a smooth coexistence between the people and U.S.-led forces.

"The most important aspect why this city is so stable is that we have someone like Ayatollah Sistani," said Marine Major Rick Hall, whose battalion is deployed in the city 180 kilometres (110 miles) south of Baghdad.

At a former institute of technology, Hall and his men do not hide their admiration for Sistani, a leading Iraqi Shiite cleric of Iranian origin and a prominent member of the Hawza -- the highest Shiite authority.

"He has remained non-political and he has been talking to the people, communicating to them to join in this cooperative effort. He has a huge influence," said Hall.

"I never met him, but I definitely would like to meet him, everybody would like to meet him," he acknowledged.

Fatwas, or religious decrees, issued by the 73-year-old ayatollah, who suffered years of house arrest during Saddam Hussein's reign, are being respected by the Shiites, a majority in Iraq.

In nearly three months of occupation, the only calm-shattering incident in Najaf came on Thursday when a US soldier was shot dead by looters who opened fire at a joint U.S.-Iraqi patrol.