Rep. Peter Hoekstra, top Republican on the House Intelligence Committee, requested the probe into possible disclosure of U.S. secrets in a letter to Mike McConnell, who supervises spy agencies as director of national intelligence.
"It would be a serious breach at CIA if what this foreign investigator claims is true," said Hoekstra, R-Mich.
Dick Marty, a Swiss senator, conducted an 18-month inquiry on behalf of the Council of Europe into allegations that the CIA interrogated major terror suspects at secret prisons in several European countries.
Marty's report, released last month, says some of his sources were within the CIA. He said the sources were dissatisfied with the detention policy pursued under then-Defense Secretary Donald H. Rumsfeld.
"There were huge conflicts between the CIA and Rumsfeld," Marty said Tuesday in Brussels, Belgium, where European Union lawmakers questioned him about his report. "Many leading figures in the CIA did not accept these measures at all. They felt they were counterproductive."
In his letter, Hoekstra said that "every intelligence official swears an oath to protect the people and national secrets of this great land. To willingly discuss the details of any classified government program with an agent of a foreign power without authorization is absolutely unconscionable. This would represent an egregious violation of the public's trust."
The lawmaker urged McConnell to determine the validity of the Swiss investigator's claims and to request a criminal referral from the Justice Department if they are true.
If the claims aren't true, Hoekstra asked McConnell to demand that the Council of Europe force Marty to stop making false claims about CIA officials in an attempt to bolster the validity of his report.
Vanee Vines, a spokeswoman for the director of national intelligence, had no immediate comment on Hoekstra's letter but said, "It will be considered."