It’s war between Condé Nast and former French Vogue editor Carine Roitfeld. Sources say Condé’s International chairman Jonathan Newhouse has been ordering photographers and editors not to work with Roitfeld for her new magazine CR Fashion Book.

In September, Roitfeld plans to launch the biannual title with Fashion Media Group LLC — home of V, V Man and Visionaire — out of an office at The Standard, East Village hotel.

We’re told that after Roitfeld announced her plans for the magazine, Newhouse sent word to photographers including Mario Testino, Craig McDean, David Sims and the Mert Alas and Marcus Piggott team “reminding” them of their exclusivity with Condé Nast to shoot for its titles including Vogue, W, Glamour, Vanity Fair and Allure.

“A call did go out from Jonathan Newhouse’s office with the idea to reinforce the fact that people were under exclusive contracts,” preventing them from working elsewhere, a source told us.

Even those who aren’t bound contractually to Condé Nast have been discouraged from working with Roitfeld, fearing backlash from the publisher, our sources said.

“Everyone is buzzing about the Condé roadblocks against Carine,” one fashion insider said. “People love Carine but are more frightened of the Condé Nast machine.”

Roitfeld left French Vogue under controversy in 2011, with whispers that Newhouse himself grew tired of the editor after a controversial Tom Ford-themed issue featuring styled-up young girls in heavy makeup and ball gowns.

Roitfeld doesn’t seem to harbor bad blood, telling Women’s Wear Daily in April: “Vogue is a very beautiful magazine, an institution, and I learned so much working there . . . You can’t put yourself into competition with a magazine like Vogue; you have to create something new, something different.

Reps for Condé Nast and the photographers didn’t get back to us. A rep for Roitfeld couldn’t be reached.