The commentary on the WSJ website addressed what Alito referred to as "charges" by journalists from ProPublica that he had failed to recuse from cases in which an entity connected to hedge fund founder Paul Singer was a party, and to report certain gifts on mandatory annual financial disclosure forms, such as a private flight to Alaska for a fishing trip.

"Neither charge is valid," Alito wrote.

A spokesperson for ProPublica said: "We don't comment on unpublished stories."

Alito's comments come as the court has been embroiled in ethics controversies - in particular revelations about ties between conservative Justice Clarence Thomas and a Texas billionaire. Opinion polls have revealed a sharp drop in public confidence in the top U.S. judicial body.

Alito wrote that for the private flight to Alaska, which appears to have taken place in 2008, Singer "allowed me to occupy what would have otherwise been an unoccupied seat."

He said he stayed in a "modest one-room unit at the King Salmon Lodge, which was a comfortable but rustic facility."

Alito said the justices commonly interpreted financial disclosure requirements to mean that "accommodations and transportation for social events were not reportable gifts."

The Judicial Conference, the policymaking body for the broader federal judiciary, recently tightened its regulations related to that exemption, including requiring transport by private jet to be disclosed.

"The flight to Alaska was the only occasion when I have accepted transportation for a purely social event, and in doing so I followed what I understood to be standard practice," Alito wrote.

Alito also said he had "no obligation" to recuse in any case connected to Singer, with whom he has spoken to a handful of times.

In one case that the Supreme Court heard in 2014 involving a unit of Singer's Elliott Management, Alito said: "I was unaware of his connection with any of the listed entities, and I had no good reason to be aware of that."