* European Court of Human Rights to hear case in December
* Court to review allegation Poland hosted secret CIA jail
* Rights group say hearing should be held in public
* Poland widens its own, separate investigation (Adds new alleged detainee in paragraphs 14-16)
By Christian Lowe
WARSAW, Oct 30 (Reuters) - Poland's government has asked the European Court of Human Rights to exclude the media and the public from a court hearing on whether Poland hosted a secret CIA prison on its territory.
The request for a private hearing was criticised by a Polish human rights group, which accuses the state of trying to conceal its involvement in the CIA's "extraordinary rendition" programme behind a veil of secrecy.
The Strasbourg-based court scheduled a public hearing for Dec. 3 to hear arguments in the cases of two men who say they were held in a CIA-operated jail in Poland. It will be the first time the allegations have been tested in open court.
Since then, Poland's government has submitted a request to the court asking for the hearing to be held in private, a spokeswoman for the court told Reuters. "This request will be examined by the court shortly," she said.
The Polish Foreign Ministry, which oversees relations with the court, declined to comment. In a statement sent to Reuters, it referred inquiries to the court instead.
The government has in the past cited national security concerns to explain why it wanted parts of the court process to be kept confidential.
Adam Bodnar, vice-president of the Warsaw-based Helsinki Foundation for Human Rights, said much of the evidence about the alleged CIA jail was already in the public domain, so there was no point treating it as secret.
"We should have the right to review this case in public," said Bodnar, whose organisation has uncovered evidence of Polish cooperation with the CIA. "I do not see a reason for confidentiality of proceedings."
The United States has acknowledged that, after the Sept. 11 attacks in 2001, it had facilities around the world as part of a programme of "extraordinary rendition" to detain and question suspected al Qaeda militants.
Keeping the detainees on foreign soil meant they were not entitled to the protection afforded under U.S. law.
The case before the European Court was brought by lawyers for two men, Saudi-born Abu Zubaydah, and Saudi national Abd al-Rahim al-Nashiri.
Both men, who are now in the U.S. military's Guantanamo Bay jail on Cuba, say they were held by the CIA on the grounds of an intelligence training facility near the village of Stare Kiejkuty, in northeast Poland.
Polish prosecutors are working on their own criminal investigation into the allegations of a CIA jail, which is separate to the case being heard in Strasbourg.
Nashiri and Zubaydah are already listed as parties to that investigation. A third man who also says he was detained illegally in a CIA jail in Poland, Yemeni national Walid Bin Attash, has now been granted the same status, his lawyer said.
This status shows that prosecutors believe Attash's allegations are serious and worth investigating, the lawyer, Mariusz Paplaczyk, told Reuters on Wednesday.
Piotr Kozmaty, a spokesman for the prosecutor's office which is handling the case, said a new alleged detainee had been added to the case, but did not give the man's name.
Polish officials deny hosting any CIA jails, though they do say that in 2002 and 2003, aircraft used by the CIA landed, without border or customs controls, at a remote airfield in northern Poland, near the site of the alleged jail.
If Polish officials were complicit in the setting-up of a secret jail, that would be against Polish law and in violation of international treaties, rights campaigners say.
The government says the investigation under way inside Poland is independent and should run its course before the European court gets involved in the case.
Rights activists and lawyers for the alleged detainees say the Polish investigation, which began in March 2008, is being stalled because a trial will embarrass the Polish state. Prosecutors and the government deny that. (Reporting by)
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