Associate Justice Clarence Thomas said Friday he was not required to disclose the trips he and his wife took that were paid for by a Republican megadonor, Harlan Crow.

Describing Mr. Crow and his wife, Kathy, as “among our dearest friends,” Justice Thomas said in a statement that he was advised by colleagues on the nation’s highest court and others in the federal judiciary that “this sort of personal hospitality from close personal friends, who did not have business before the Court, was not reportable.” Justice Thomas did not name the other justices or those in the judiciary with whom he had consulted.

The liberal investigative journalism organization ProPublica reported Thursday that Justice Thomas, who has been a Supreme Court justice for more than 31 years, has for more than two decades gone on luxury trips from Mr. Crow nearly every year.

Justice Thomas, 74, and his wife, Virginia, have traveled on Mr. Crow’s yacht and private jet as well as stayed at his private resort in New York’s Adirondack Mountains, ProPublica reported. A 2019 trip to Indonesia the article detailed could have cost more than $500,000 had Justice Thomas chartered the plane and yacht himself.

Supreme Court justices, like other federal judges, are required to file an annual financial disclosure report which asks them to list gifts they have received, but provides exemptions for hospitality from friends.

Ethics experts have offered conflicting views about whether Justice Thomas was required to disclose the trips. Last month, the federal judiciary bolstered disclosure requirements for all judges, including the high court justices, although overnight stays at personal vacation homes owned by friends remain exempt from disclosure.

A law professor at Indiana University who studies judicial ethics, Charles Geyh, wrote in an email that he doubts any justice would have advised Justice Thomas against disclosure if he had laid out the details in ProPublica’s report: “hundreds of thousands of dollars in luxurious travel and accommodations at exotic locales spanning decades, from a benefactor who has a deeply rooted partisan and ideological interest in the future of the Court on which the justice sits.”

A University of Pittsburgh ethics authority, Arthur Hellman, said that even if Justice Thomas could reasonably have believed he did not have to report Mr. Crow’s gifts, he still should have. “It would have been preferable in the sense of public confidence in the courts if he had disclosed,” Mr. Hellman said.

Justice Thomas, the longest-serving member of the court, said he has always tried to comply with disclosure guidelines. Regarding the recent changes, “It is, of course, my intent to follow this guidance in the future,” he said in the statement.

The new reporting requirements appear to cover almost all the travel and lodging Mr. Crow provided, Mr. Hellman said. The mere need to disclose could make judges more reluctant to accept the gifts in the first place, he said.

“If I had to predict, I’d say Justice Thomas will be seeing less of Harlan Crow’s luxurious properties,” Mr. Hellman said.

Democratic lawmakers said the ProPublica story was the latest illustration of why the Supreme Court should adopt an ethics code and further tighten the rules on travel and other gifts.

It is by no means clear that the justices will agree to subject themselves to an ethics code or that Congress will seek to impose one on the court.

Justice Thomas did not refer to any individual trips paid for by Mr. Crow. Yet he said, “As friends do, we have joined them on a number of family trips during the more than quarter century we have known them.”

Last year, questions about Justice Thomas’ ethics arose when it was disclosed that he did not step away from election cases following the 2020 election despite the fact that his wife, a conservative activist, reached out to lawmakers and the Trump White House to urge defiance of the election results.

Associated Press