The Coalition Provisional Authority (CPA) posted dozens of posters near the gates to its Baghdad headquarters, stating that protests must be peaceful.

The area has been the scene of dozens of demonstrations by Iraq's bloated community of unemployed and other groups taking advantage of the freedom of speech that came with the fall of Saddam Hussein's regime in April.

"Liberty equals responsibility," the posters read. "After the liberation, you have the right to demonstrate without fear, but with this right you have the responsibility to protest peacefully.

"Violence against citizens, Iraqi police or coalition forces will not be tolerated and will be dealt with forcibly," it added.

The posters appeared at the end of a week of daily protests outside CPA headquarters by a group calling itself the Union of the Unemployed and boosted by ultra-leftist Communist groups, demanding jobs or financial support from the occupying coalition. A handful of protests have turned deadly in Iraq since Saddam's regime collapsed April 9, while many other tense stand-offs between demonstrators and coalition troops saw violence narrowly averted.

Americans shot dead at least 16 Iraqi demonstrators in late April in the flashpoint town of Fallujah.

Meanwhile, the US army said Tuesday it had arrested four fugitive members of the disbanded Baath party during several overnight raids in the region of Tuz, 150 kilometres (95 miles) north of Baghdad.

"Out of seven raids in the Tuz area, nine people were eventually detained, four of whom were Baath party members we were targeting," said Lieutenent Colonel Bill MacDonald, spokesman for Task Force Iron Horse, which is conducting the crackdown on Saddam Hussein loyalists in the region.

MacDonald gave no further details on the identities of those arrested or their role in Saddam's ousted regime.

He added that a cache of weapons and ammunition was discovered Monday by US forces in an open-air site close to Tuz, near the highway that links Baghdad with the oil-rich northern city of Kirkuk.