There’s a battle royal going on behind the scenes at CSI: Crime Scene Investigation - should Gil Grissom leap into the sack with Sara Sidle?

Fans of TV’s top-rated show, now in its fourth season, think it’s a pretty hot drama. But backstage fights over what should happen between the characters played by William Petersen and Jorja Fox make the on-screen happenings seem like winter in Antarctica, say insiders.

“The production team has been torn apart,” a source says.

“One group believes workaholic Grissom is so emotionally stunted that he could never have an affair and that’s the way he should be played.

“But the rival faction is campaigning for some action between the sheets.

“They point out that after all, it’s unrealistic to believe that when two available people flirt so much it won’t lead to an affair.

“To have them flirt without a sexy outcome is like kissing your sister, and the viewers will start to yawn, they say.”

The stars who play the two characters involved can’t agree on how far to take things, either.

Petersen, 50, wants the pair to explore their growing attraction, as long as it doesn’t turn the show into a soap opera, say insiders.

But Fox, 35, believes that although their constant flirting is a great dynamic for creating tension, a segue into sex would detract from the show’s strong stories.

She admits she’ll be making goo-goo eyes at Grissom for the foreseeable future.

“I think we’re going to have a very personal year for the characters,” she reveals, “more-so that we’ve ever done.”

The backstage bickering over the steamy issue has spilled onto the Internet, where fans are airing their opinions online. And now that the new CSI season is in full swing, the debate is healing up.

One group of fans even posted an open letter to the shows producers, urging them to press ahead with the Grissom-Sara love match.

“We feel that a relationship would provide a human element to the show,” the petition says.

Other online fans agreed, licking their lips at the prospect of the two stodgy characters getting intimate for a change.

But some viewers are squarely against pairing up the investigators in the bedroom.

“It does nothing for the show,” one disappointed fan complains.