Europe:Council of Europe investigator Dick Marty said yesterday that he stood by the findings of his recent report, which alleged that Poland and Romania had hosted secret CIA prisons.
The Swiss senator also pledged not to reveal the identity in any future court case of any of the 30 or so "anonymous sources" he used to compile his report.
Mr Marty was responding to comments made by Poland's former national security adviser, Marek Siwiec, who told the Polish media that he would sue Mr Marty for libel.
Mr Siwiec said he had demanded that Mr Marty remove his name from the controversial report, in which he was mentioned as one of the officials who was aware of and could be held accountable for the prisons.
"I did not receive any answer from Marty, so I will be forced to start court proceedings for libel, for actions that were intended to harm my good name," Mr Siwiec, who is now a vice-president of the European Parliament, told the PAP news agency.
Poland and Romania have both strenuously denied hosting CIA-run prisons to detain and interrogate possible terrorist suspects.
They also dismissed the findings of Mr Marty's report, which were published last month after a year-long investigation. In the report Mr Marty alleged that Poland housed some of the CIA's most sensitive prisoners under a post-September 11th pact to hunt down and interrogate "high value" terrorist suspects wanted by the US.
Mr Marty based his report on interviews with more than 30 European and US intelligence officials, who were not named.
The Swiss investigator has defended the use of anonymous witnesses, saying his sources needed to be protected because they would face charges of high treason in their countries if their identity was revealed.
US president George Bush acknowledged last year that the CIA had held top al-Qaeda suspects in secret overseas detention centres, but did not say in which countries.
In a phone interview with The Irish Timesyesterday, Mr Marty said he should be covered by immunity from prosecution provided by the Council of Europe parliamentary assembly. He said he stood by the findings of the investigation and the published report.
"We have sources that are absolutely credible," said Mr Marty, who also pledged not to reveal the identity of any sources in any future libel action.
The parliamentary assembly of the Council of Europe would not comment on the threat of legal action when contacted yesterday.