Suspects will also have to give testimony and allow property to be searched and seized even if what the suspect is accused of is not a crime in Ireland.

Under 'instruments of agreement' signed last week by Justice Minister Michael McDowell, Ireland and the US pledged mutual co-operation in the investigation of criminal activity. It is primarily designed to assist America's so-called 'war on terror' in the wake of the September 11 atrocities.

The deal was condemned yesterday by the Irish Council for Civil Liberties (ICCL) as "an appalling signal of how the rights of Irish citizens are considered by the minister when engaging in international relations". The ICCL said it appeared to go far beyond even what has been agreed between EU countries.

On signing the agreement, the minister said that "the international community must do everything it can to combat terrorism with every means at its disposal.

"Ireland will not be found wanting," he added.

The treaty will give effect to agreements on Mutual Legal Assistance and Extradition signed by the EU and the US in June 2003. These are aimed at building on mutual assistance and extradition arrangements.

Although the Department of Justice insists that the arrangement merely updates existing agreements, it goes much further. The US may ask Irish authorities:

To track down people in Ireland.

Transfer prisoners in Irish custody to the US.

Carry out searches and seize evidence on behalf of the US Government.

It also allows US authorities access to an Irish suspect's confidential bank information. The Irish authorities must keep all these activities secret if asked to do so by the US.

The person who will request co-operation is US Attorney General Alberto Gonzales, the man who, as White House counsel, instigated the notorious 'torture memo' to US President George W Bush which advised how far CIA agents could go in torturing prisoners. The person to whom the request is sent is the Minister for Justice.

About 20,000 immigrants, who have not been charged with any crime, are currently in prison in the US. In two recent US Supreme Court cases, the US Government argued that US citizens could be imprisoned indefinitely without charge if the president designated them as "enemy combatants".

ICCL director Aisling Reidy said: "An extraordinary aspect to this treaty is, despite its scope and its potential to violate basic constitutional and human rights, that all this happened without debate or transparency.

"To agree to give such powers to a government which has allowed detention of its own citizens without access to a lawyer for over a year, which has legitimised Guantanamo Bay and the interrogation techniques there, without public debate, is an appalling signal of how highly or not the rights of Irish citizens are considered by the minister when engaging in international relations."

The Department of Justice said it was wrong to say the treaty happened without debate, as the agreements update and supplement existing arrangements, and the EU-US agreement has been scrutinised by the Oireachtas four times since December 2002.

A spokesperson also rejected that the measures go beyond what was agreed between EU countries.

Legislation will be required to give effect to some elements of the Mutual Legal Assistance Instrument. The necessary provisions will be contained in the Criminal Justice (Mutual Assistance) Bill which Mr McDowell expects to publish shortly.