Sen. Robert Menendez (D-N.J.), center, arrives at court with his children, Alicia Menendez and Robert Menendez Jr., for his federal corruption trial in Newark on Sept. 6. (Seth Wenig/AP)

The judge overseeing the bribery trial of Sen. Robert Menendez ripped into prosecutors Thursday for trying to focus on what he called “tabloid’’ details — an unusual description for dry testimony about a series of emails about a hotel reservation.

U.S. District Judge William Walls stopped testimony for 20 minutes in which he tongue-lashed prosecutors for their painstaking recounting of emails used to book a luxury hotel in Paris for the New Jersey Democrat in 2010. The three-day hotel stay is a central part of the Justice Department’s case.

Menendez’s friend, wealthy eye doctor Salomon Melgen, paid for the senator’s nearly $5,000 hotel stay, and prosecutors contend the gift is one of the most incriminating bribes the senator received, in exchange for which Menendez repeatedly did favors for Melgen’s business and personal interests.

But on Thursday, the judge was clearly fed up with prosecutors’ focus on the details of the Paris hotel room.

He halted questioning of FBI supervisory analyst Jane Ruch about emails discussing Menendez’s lunch plans during the trip. After having the jury leave the courtroom, the judge lit into Justice Department lawyers.

“I don’t think it’s a sin for him to want a limestone bath, per se,’’ Walls said. “It’s tabloid in nature. . . . Whether these defendants engaged in bribery does not depend on whether the senator chose a more expensive room. We’re not talking about Days Inn.’’

The prosecutor, J.P. Cooney, tried to change the judge’s mind, saying the details of the hotel room pricing are important evidence “because the value of these rooms far outstrips what he could afford to pay either in points or in cash.’’

The judge cut him off and said he was concerned prosecutors were trying to create an unfair inference because the emails showed Menendez went to Paris with a woman friend.

“It’s ridiculous, what you’re asserting,’’ Walls told the prosecutor. “You’re saying because a person, according to you, wants to stay at a hotel with another person that he then goes out and solicits a bribe. Is that what you’re telling me?”

The exchange prompted Menendez’s lawyer to interject: “This person is actually just a friend, and it is not anybody to be shacked up with.’’

Cooney, the prosecutor, then insisted he was not trying to suggest to the jury Menendez “went to Paris in order to shack up with another person.’’

Menendez and Melgen are on trial for what prosecutors call a years-long scheme of corruptly swapping gifts for official favors.

According to the indictment, those gifts allegedly include private jet rides, hotel stays and more than $750,000 in campaign and legal defense donations.

Prosecutors say Menendez sold his office because he wanted the perks of wealth, but he could not afford them on his senator’s salary.

In exchange, prosecutors say, the New Jersey senator repeatedly did favors for Melgen, including helping the doctor’s girlfriends get visas to the United States, interceding with Medicare officials when the doctor got into an $8.9 million billing dispute, and trying to assist the doctor in a separate, stalled business contract he held involving port security.

Lawyers for Menendez and Melgen say the two men are decades-long friends who took vacations together and acted out of friendship, not corrupt intent.

“When you do things for friends because you love them like a brother, that’s not a bribe,’’ Melgen’s lawyer, Kirk Ogrosky, said.

The trial is expected to last more than a month, and the judge’s admonitions, coming on the first day of testimony, aimed in part to encourage lawyers to speed up their questioning.

Menendez and Melgen have denied wrongdoing, and the senator has said he may have to miss some of the trial if he’s needed in Washington for a close vote in the Senate.