In a statement, Thomas also said that he has always sought to comply with disclosure guidelines.

ProPublica reported on Thursday that the long-serving justice accepted expensive trips from Crow over decades despite federal law requiring the disclosure of most gifts, prompting Senate Democrats to call for an investigation.

"Early in my tenure at the (Supreme) Court, I sought guidance from my colleagues and others in the judiciary, and was advised that this sort of personal hospitality from close personal friends, who did not have business before the Court, was not reportable," Thomas said.

Citing new guidelines taking effect by the Judicial Conference responsible for financial disclosure requirements for the entire federal judiciary, Thomas added, "It is, of course, my intent to follow this guidance in the future."

For several years, questions have been raised about weak disclosure rules relating to trips and other types of gifts, as well as recusal rules, for judges.

U.S. Supreme Court justices and federal judges must make public more details about any free trips, meals or gifts they receive under new regulations adopted at the urging of lawmakers and judicial transparency advocates.

Democrats in Congress are seeking legislation that they say would bring even more rigor to ethical requirements in the judicial branch.

In his statement, Thomas said he and his wife, Virginia "Ginni" Thomas, had long counted Harlan and Kathy Crow among their dearest friends.

"As friends do, we have joined them on a number of family trips during the more than quarter century we have known them," Thomas said.

In a statement to ProPublica, Crow said he had "never sought to influence Justice Thomas on any legal or political issue."