The Swiss branch of Human Rights Watch (HRW) has called on the Swiss government to do more to expose alleged CIA detention camps in eastern Europe.
At the opening of its Zurich office, HRW accused the Swiss authorities of failing to support a Council of Europe investigation into the existence of the camps.
The Council of Europe investigation, headed by Swiss senator Dick Marty, focuses on reports that the US has established secret prison camps in countries including Poland and Romania to interrogate suspected terrorists.
"The Swiss government should be putting much more energy into making the governments of Poland and Romania provide an explanation than prosecuting those who reveal evidence," said HRW executive director, Kenneth Roth.
"Secrecy is fine for legitimate government activity, but not to cover-up human rights abuses," Roth added.
He also urged the Swiss government not to go through with its threat to prosecute the SonntagsBlick newspaper, which printed secret service documents allegedly showing evidence of detention centres.
Roth's comments came on the same day that a parliamentary sub-committee cleared the cabinet of having knowledge about alleged CIA prisoner flights over Swiss airspace. It also said it had found no evidence of such flights or of any detention centres in Europe.
In his address, Roth said he was convinced that such camps existed and condemned world leaders for failing to uncover the facts.
"Dick Marty is doing a very conscientious job, but it is unfair, wrong and hypocritical for governments to stand back, arms folded, waiting for him to uncover dark secrets," Roth told the meeting.
Roth believes Switzerland has a key role, as guardian of the Geneva Conventions, for improving human rights around the world.
He said Switzerland was now a far more credible voice for human rights than the US and could act more efficiently than the cumbersome 25-nation European Union.
The Swiss Federal Prosecutor's Office opened a criminal investigation last month to establish whether CIA flights over Swiss airspace, allegedly carrying suspect terrorist prisoners, were illegal.
But on Tuesday a parliamentary sub-committee said that, according to its findings, the government had acted correctly in its handling of the affair.
It also praised the intervention of Foreign Minister Micheline Calmy-Rey. Marty had previously accused European governments of compliance in the matter.
The committee said no evidence of the flights or of the alleged prisons had been found.
swissinfo, Matthew Allen in Zurich
Human Rights Watch was founded in 1978 and tracks developments in 70 countries.
The Zurich branch, which opened on Tuesday, is charged with raising awareness of human rights issues among the Swiss, finding funds for investigation work and lobbying the Swiss government.
Besides Zurich, HRW has an office in Geneva which is directed towards an international audience.
On November 2, the Washington Post published an article that alleged that the United States was using secret prison camps in eastern Europe to interrogate terror suspects.
Switzerland has asked Washington for explanations about four landings at Geneva airport and 30 flights in Swiss airspace.
On January 8, SonntagsBlick printed documents from the Egyptian authorities, leaked to the newspaper from the Swiss secret service, allegedly pointing to the existence of CIA prison camps in Europe.
In compliance with the JTI standards