Iraqi forces surround Sadr's office in Najaf

"The Iraqi national guard and police forces have encircled the office since this morning and are attempting to raid it," Sheikh Ahmed Shaibani said.

He said Sadr officials had prevented Iraqi forces from entering the premises and are demanding an authorisation signed by Grand Ayatollah Ali al-Sistani before they will allow the office to be searched.

Several demonstrations have been staged in recent days by Najaf residents demanding that Sadr and his Mehdi Army militia leave the holy city, blaming him for the destruction which resulted from weeks of fighting with US troops around the Imam Ali shrine.

The Iraqi government has accused Sadr supporters of killing and torturing scores of people during the standoff.

Earlier Iraqi forces backed by US troops swept through the northern Iraqi city of Kirkuk overnight and arrested about 25 suspects, including a fugitive security chief under the former regime.

"Elements from the national guard and police, backed by US troops, raided a number of houses after receiving information about some terrorist elements and we arrested 25 suspects," Kirkuk police chief Turhan Yusef said.

Another police officer in the oil-rich city said Iraqi forces had also arrested Sirhan Ahmed Khalaf, the head of security in the restive city of Samarra under the former regime of Saddam Hussein.

Meanwhile, three Jordanians, a Sudanese and a Turkish nationals held hostage by an Islamic militant groups in Iraq were released yesterday, Jordanian Foreign Minister Marwan Moasher announced.

"A short while ago the hostages were released. They are four, a Sudanese national and three Jordanians," he told a news conference in Amman. "They were released this morning after some (mediation) efforts."

The announcement came as Iraqi Foreign Minister Hoshyar Zebari was due to begin a two-day visit to Jordan during which he was set to hold talks with Moasher.

Moasher identified the freed Jordanians as Mohammad Beshir, Kassem Gharibi and Nabil Mussa Mohamad, adding that they were expected to return to Jordan later Monday.

An Iraqi militant group had announced in a videotape aired Sunday by Al-Jazeera television that it had taken four Jordanian drivers hostage.

A group calling itself "Shura Council of the Mujahedeen of Fallujah," named after a Sunni Muslim bastion of the anti-US insurgency, said the four "were ferrying material to US forces in Iraq."