An al-Jazeera journalist who was imprisoned in Guantánamo Bay plans to launch a joint legal action with other detainees against former US president George Bush and other administration officials, for the illegal detention and torture he and others suffered at the hands of US authorities.

The case will be initiated by the Guantánamo Justice Centre, a new organisation open to former prisoners at the US base, which will set up its international headquarters in Geneva, Switzerland, later this month.

"The purpose of our organisation is to open a case against the Bush administration," said co-founder Sami al-Haj, an al-Jazeera reporter from Sudan who was illegally detained by US authorities for over six years after being captured while he was working as a cameraman. He was freed in May 2008.

"We need to start our organisation first and then we will prepare a whole case. We don't want to do this case by case," said the 40-year-old journalist during a recent visit to Oslo.

"We are in the process of collecting information from all the people, such as medical evidence. It takes time," he said.

He added: "I need them to go to court … we don't want [what happened to us] to be repeated again."

The legal action may be modelled on an action against General Augusto Pinochet, who was arrested in the UK in 1998 at the request of a Spanish prosecutor for the alleged murders of Spanish citizens in Chile under his dictatorship.

Al-Haj said: "I spoke to my lawyer, who advises me to do this in Europe. The courts do not have the power to bring [US officials] by force, but at least they can't visit European countries. If they do, [the authorities] would catch them and send them to court."

The Guantánamo Justice Centre, which will be led by British ex-detainee Moazzam Begg, will open a British-based branch this month in addition to its Geneva headquarters.

Al-Haj, who is back at work for the Arabic satellite channel in Qatar, is in frequent contact with Guantánamo detainees, both past and present.

"Torture is continuing in Guantánamo," al-Haj said. "Obama needs to close Guantánamo immediately."

Al-Haj said he was questioned by British intelligence officers during his detention, once in Kandahar in March 2002, and another time at Guantánamo later that same year. He said: "They asked me questions about al-Jazeera, whether it had links with al-Qaeda. They asked me questions about the British detainees at Guantánamo.

"They told me I should cooperate with the Americans and work as a spy," upon his release. He said he was not mistreated by the British intelligence officers.

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