'There must be an urgent enquiry into these reports. There are very real concerns that the US forces may have used excessive force,' Amnesty International said.

'The USA and the UK must ensure that the rights of freedom of expression and assembly are not arbitrarily restricted.'

The organisation believes that these latest incidents simply confirm the urgent need for police forces, not the military, to be dealing with law and order issues.

Amnesty International is also calling on the USA and the UK to deploy forces in sufficient numbers and with the right training and equipment to restore law and order, until Iraqi police forces can operate effectively.

The latest incident occurred whilst townspeople were demonstrating about the shooting of Iraqi civilians by US troops on Monday night.

On Monday, between 13 and 17 civilians were shot dead and more than 70 were wounded when soldiers occupying a local school fired on demonstrators protesting against the US presence in Iraq.

US troops say that they came under fire after asking a group of about 200 people to disperse, and had to respond. Local residents state that approximately 200 unarmed people were protesting and carrying pictures of former President Saddam Hussein.

US and UK forces, as the occupying power, are under an obligation to implement human rights and humanitarian law in the areas under their control. The Basic Principles on the Use of Force and Firearms by the Law Enforcement Officials - including police and soldiers - require that use of force and firearms should be a last resort, and used 'only if other means remain ineffective or without any promise of achieving the desired result'. (Principle 4) whenever force or firearms are used this should be proportionate to the seriousness of the offence and the legitimate objective to be achieved; and minimize damage and injury.

A full copy of Amnesty International's report: Iraq: Responsibilities of the occupying powers is available online.