A USTIN Powers, the shagadelic British spy, is heading back into theaters next month with a sequel to the 1997 hit – and he’s now also slated to become a cartoon on HBO.

Details of the show have become one of TV’s best-kept secrets because the studio behind the animated version of the psychedelic-superspy is going the extra mile to keep the animated show under wraps.

A cartoon featuring England’s psychedelic super-groovy spy is currently in development at New Line Cinema, studio sources have confirmed.

But ferreting out the details may require the shagadelic talents of Powers himself.

New Line owns and distributed the box office blockbuster “Austin Powers: International Man of Mystery,” and is also responsible for the forthcoming “Spy who Shagged Me.”

Studio officials would not comment about the cartoon, and an HBO spokeswoman said she could not “confirm or deny” a report that the pay-cable channel wants to air the show when it is done.

“We’re keeping this one pretty close to the vest,” a New Line official said.

Both theatrical films star “Saturday Night Live” alumni Mike Myers as a dentally challenged British super-spy more promiscuous than James Bond. Powers was flash-frozen in the 1960s and then thawed out in the 1990s to fight his nemesis Doctor Evil, who is also played by Myers.

The cartoon is expected to feature a plot similar to the films, and would most likely feature Myers’ voice in the lead roles.

“The Spy Who Shagged Me” is slated to be released in theaters June 11.