NEW YORK — The New York Times acknowledged Tuesday that a reporter who wrote an acclaimed 2005 article about a teenage Internet pornographer helped gain the boy’s trust by sending him a $2,000 check.

Former Times staff writer Kurt Eichenwald made the payment in June 2005 to Justin Berry [both pictured], who at the time was an 18-year-old star in a seedy network of child-porn sites.

Six months later, Berry became the leading figure in Eichenwald’s expose on Web sex sites run by teenagers. The Times investigation prompted congressional hearings, led to arrests and fueled reforms in the way Web-hosting companies screen their clients.

The story also garnered attention for the unusual relationship between Eichenwald and his primary subject.

In the months before the story ran, Eichenwald persuaded Berry to quit the porn business, stop using drugs and become a law enforcement informant.

The Times outlined the unorthodox nature of the intervention in a sidebar accompanying its original report and in a follow-up column by the paper’s public editor, Byron Calame.

Times editors, however, said they were unaware that Eichenwald had also given the teen money.

“The check should have been disclosed to editors and readers, like the other actions on the youth’s behalf,” the paper said in a note published Tuesday.

In a telephone interview with The Associated Press, Eichenwald, who left the Times in October, explained that he had sent the teen a check as part of a ploy to learn his true name and address.

At the time, he said, he didn’t intend to write about Berry, but had come across his distressing Web identity while researching an unrelated article. Eichenwald said he and his wife decided to try to get help for the young man.

“We were gambling 2,000 on the possibility of saving a kid’s life,” he said.

Eichenwald said that when he finally decided to write about Berry after meeting him in person, he asked for the money back. Most newspapers, including the Times, prohibit reporters from paying sources. The $2,000 was eventually repaid by Berry’s grandmother, he said.

For months, media analysts debated whether Eichenwald had crossed an ethical line by getting too close to his subject. The University of Oregon named Eichenwald a 2006 winner of the Payne Awards for Ethics in Journalism for his actions.

On Tuesday, Eichenwald was in Detroit, waiting to testify in the criminal trial of a man accused of molesting Berry.

The defendant, Ken Gourlay, is one of several men arrested on charges involving child pornography after Berry began working with the Justice Department. One of them, Gregory Mitchel, pleaded guilty last year and was sentenced to 150 years in prison.

Eichenwald acknowledged that he should have disclosed his $2,000 payment to his editors, but said it slipped his mind amid the other complicated ethical questions surrounding the story. He said he also didn’t feel it relevant because the payment was made at a time when he was acting on his own, rather than as a reporter.

“I know I did unusual things, and if I should have disclosed what I did as a private citizen in more detail, so be it. But put me through the same situation, I can’t say I’d do anything differently,” said Eichenwald, who now works for Portfolio, a new Conde Nast business magazine that is in the process of being launched.