Tom Cruise built a secret million-dollar underground bunker at his palatial family compound in Beverly Hills, The National ENQUIRER has learned.

Ex-members of Tom’s controversial religion, Scientology, believe the bunker was most likely a “hideout” for the superstar, then-wife Katie Holmes and their daughter, Suri – in preparation for the end of the world!

Tom splashed out $35 million for the 10,000-square-foot mansion in April 2007.

The home sits on 1.3 acres and includes a long gated driveway, a pool and a tennis court.

Then, according to permit documents from the City of Beverly Hills Building and Safety division obtained by The ENQUIRER, Tom spent millions more to excavate the bedrock underneath the estate’s existing tennis court!

Tom built what appears to be an underground shelter that includes a basement, gym and laundry facility to be used as a “day staff lounge” with two bedrooms, according to the plans.

But the “bunker” sounds similar to Scientology’s “doomsday preparedness” plans, insisted former church insider Marc Headley.

Apparently, Scientologists believe that the evil, deposed galactic ruler Xenu is set to attack Earth, and they’ll need a safe place to survive!

“When something goes down, they know they’re going to need a place to hide out,” said Marc, who spent 15 years as an employee at Scientology’s international headquarters near L.A.

That paranoia extends to Scientology’s fear of a nuclear holocaust.

As a result, the church built several bunkers, called “time capsules,” into the sides of mountains.