LOS ANGELES — Fast food chain Jack in the Box Inc. can continue to air TV ads that make a rival restaurant the butt of its jokes, a federal judge ruled yesterday.

U.S. District Judge Andrew Guilford said he wanted to see more evidence of actual harm before barring the cheeky ads that suggest rival company CKE Restaurants Inc., which operates Carl's Jr. and Hardee's, uses cow anuses to make its Angus beef hamburgers.

CKE sued Jack in the Box in May over two TV ads, including one in which executives laugh hysterically at the word "Angus" and another where the chain's mascot, Jack — a man with the round clown head and pointy nose — is asked to point to a diagram of a cow and show where Angus meat comes from.

"I'd rather not," Jack replies.

The employee asking the question traces a circle in the air with his pen while pronouncing the word Angus.

The lawsuit claims the TV spots confuse consumers by comparing sirloin, a cut of meat found on all cattle, with Angus, which is a breed of cattle.

The judge rejected a CKE survey of 404 people that found 36 percent thought Angus beef comes from the rump of a cow.

The company yesterday said it might try again for an injunction before a trial.

"If we do another survey and come up with quantifiable evidence, we'd probably go back in," CKE chief executive Andrew F. Puzder said. "And if not, then we'll argue it out in trial."

A call to Jack in the Box for comment was not immediately returned yesterday.

CKE is known for running often controversial ads for its chains, including one featuring a scantily clad Paris Hilton washing a car while eating a hamburger.

Jack in the Box also runs humorous ads featuring the pingpong-headed Jack. But CKE claims the "Angus" ads have gone too far.

A hearing has been set for Aug. 20. No trial date has been set.