Model turned media mogul Tyra Banks swung the ax at her longtime “America’s Next Top Model” co-stars J. Alexander, Jay Manuel and Nigel Barker yesterday, dismissing three of the competition’s longest-running personalities in one fell swoop.

Sources tell Page Six that the three mentors were informed yesterday morning that their contracts would not be renewed for the next season.

Barker is a photographer and a judge on the program, while Alexander helped contestants work the catwalk as the “runway trainer.” Manuel served as the show’s creative director. All have been with the program since its inception, in 2003.

“Top Model” is currently in its 18th season, subtitled “British Invasion,” and features former contestants from “Britain’s Next Top Model” and designers and personalities including Marchesa’s Georgina Chapman and TV host Cat Deeley.

A show insider told us the departures were a “production decision” and that there are “major changes planned for [season] 19.”

We hear producers are looking to add a social media slant to the show, and they’ve already reached out to bloggers and fashion insiders with a strong Web presence, including street-style blogger Bryan Boy.

We revealed last September that Vogue editor-at-large Andre Leon Talley, who had been a judge on the show since Season 14, was being replaced by Kelly Cutrone, founder of public relations firm People’s Revolution, on the panel of judges.

Executive producer Ken Mok said in a statement: “Nigel Barker, Jay Manuel and J. Alexander have been an integral part of the ‘America’s Next Top Model’ brand and they helped turn this show into the household name it is today. They have been amazing assets to the show and will always be a part of the ‘Top Model’ family. We will continue to actively work with each of them on future projects.”