Hugo Tillman, a photographic assistant, said Testino pinned him down on a bed before being removed by another person.
The report on Mr Testino and Mr Weber includes on-the-record accounts from models and ex-assistants.
Fifteen current and former male models have accused commercial photographer, Bruce Weber of inappropriate behavior, saying citing "unnecessary nudity", "coercive sexual behavior", and "molestation" during photoshoots.
Model Bobby Roache said Weber tried to put his hands down Roache's pants during a casting in 2007.
Two big-name Vogue contributing photographers - one of them Mario Testino, a favorite of England's royal family - are being accused of repeatedly sexually harassing male models and assistants, apparently under the nose of editor-in-chief Anna Wintour.
While Voguehas worked with both Mario and Bruce, and with Mario as recently as their February 2018 issue, they will no longer be working with either of the photographers in light of the allegations.
A statement from Mr Weber quoted in the paper said: "I'm completely shocked and saddened by the outrageous claims being made against me, which I absolutely deny".
The firm also said several former employees it had spoken to were "shocked by the allegations" and "could not confirm any of the claims", according to The New York Times.
Testino's attorney, Andrew Brettler, said in an email to The Associated Press late Saturday, "We are not providing any further comment at this time".
Ryan Locke, a model who worked with Testino on Gucci campaigns, accused him of being aggressive and flirtatious throughout shoots, adding: "He was a sexual predator".
He claimed that when he told contemporaries he was working with the Peru-born photographer they would joke "tighten your belt", labelling him as "notorious".
Other men also told The Times that they have seen Testino fondle others or had fondled them on multiple occasions.
"I went at him, like, you better get away", Locke said.
"Sexual harassment was a constant reality", said Roman Barrett, an assistant to Testino in the late 1990s who said the photographer rubbed up against his leg with an erection and masturbated in front of him.
Several industries have been rocked by sexual-abuse allegations since women started coming forward to complain about Hollywood producer Harvey Weinstein, who has apologised for causing colleagues "a lot of pain".
Conde Nast - which publishes magazines including Vogue - has suspended all work with both photographers.
In December 2017, a male model brought a law suit against Weber claiming sexual harassment.