NEW YORK (CNN/Money) - Former Enron Chief Executive Jeffrey Skilling told investigators that financial returns some investors made through a partnership with the now-bankrupt energy trader could only have been achieved if the company was duped, a newspaper reported Wednesday.

In discussions with the Securities and Exchange Commission and an Enron investigative board, Skilling maintained that he knew nothing of the details of Enron's partnerships, specifically one known as LJM2, but that such high-rate returns, including some up to 2,500 percent, could not be reached through "arm-length transactions," according to documents and sources close to the investigation, the New York Times reported.

When SEC investigators showed Skilling documents detailing the returns, he grew agitated and told the regulators that he would have called Enron executives into a meeting and given them 24 hours to explain the documents had he known about them, according to the report.

Skilling's statements are the first time a former Enron executive has suggested that the financial dealings of former Chief Financial Officer Andrew Fastow, with regard to certain partnerships, might have been improper.

Skilling and his attorney were not immediately available for comment. Spokesmen for Fastow and Enron had no comment.