WASHINGTON

US Sen. Bob Menendez is the subject of a second federal criminal investigation, though details remain murky, according to multiple reports published Wednesday.

Nascent online news outlet Semafor broke the story, citing anonymous sources familiar with the investigation, though several other US media outlets have corroborated the ongoing probe.

Michael Soliman, an adviser for the New Jersey senator, told multiple news outlets that Menendez is aware of the probe, but added "he does not know the scope of the investigation."

"As always, should any official inquiries be made, the Senator is available to provide any assistance that is requested of him or his office," said Soliman.

Menendez is the chairman of the US Senate Foreign Relations Committee and has served in the federal legislature for three decades, first in the House of Representatives before taking office in the Senate.

He was indicted in 2015 on federal corruption charges tied to allegations that he illegally accepted favors from a Florida doctor, but the case ended in a mistrial in 2017 when jurors were unable to reach a unanimous verdict.

The sources who spoke to Semafor said the ongoing case is similar to the one launched in 2015 but involves different people.