Paris ? A European investigator said Tuesday he has found mounting indications the United States illegally held detainees in Europe but then hurriedly shipped out the last ones to North Africa a month ago when word leaked out.

Dick Marty, a Swiss senator looking into claims the CIA operated secret prisons in Europe, said an ongoing, monthlong investigation unearthed “clues” that Poland and Romania were implicated, perhaps unwittingly.

Both countries have denied any involvement, and Marty said he believed no prisoners were now being held by the U.S. in Europe. The CIA declined to comment.

“To my knowledge, those detainees were moved about a month ago, maybe a little more,” he told reporters after briefing the legal committee of the Council of Europe, a human-rights watchdog, on his findings. “They were moved to North Africa.”

Asked by The Associated Press on the sidelines of the meeting to which North African country detainees might have been moved, he said: “I would imagine that it would be Morocco – up to you to confirm it.”

Moroccan government spokesman Nabil Benabdellah denied any connection to such prisons when reports of the transfers surfaced last week. “We have nothing to do with and we have no knowledge about this subject,” he told the AP.

The Washington Post first reported allegations of secret prisons in eastern Europe and other countries on Nov. 2.

The newspaper did not name the countries, but the New York-based Human Rights Watch said it had evidence indicating the CIA transported suspected terrorists captured in Afghanistan to Poland and Romania. The conclusion was based on an analysis of flight logs of CIA aircraft from 2001 to 2004 obtained by the group.

European officials say such prisons would violate the continent’s human rights principles.

The investigator told reporters he could not offer proof that secret detention centers existed.