Former Johnny Carson sidekick Ed McMahon, shown in 2005, has been unable to work since suffering a broken neck 18 months ago, his agent says. (Diane Bondareff/Associated Press)

Ed McMahon, who for decades appeared as Johnny Carson's sidekick on The Tonight Show, is fighting to avoid foreclosure on his multimillion-dollar Beverly Hills, Calif., home, according to published reports.

McMahon was $644,000 US behind on payments on $4.8 million in mortgage loans as of February.

The Wall Street Journal first reported late Tuesday that a unit of Countrywide Financial Corp. has filed a default with the Los Angeles County Recorder's Office.

McMahon, 85, has been a pitchman for the American Family Publishers' sweepstakes and other products.

However, he has been unable to work since he broke his neck 18 months ago, said his spokesman, Howard Bragman.

McMahon has required surgery and been in rehab to regain physical movement.

"There are plenty of people affected by the weak economy, bad housing market or bad health," Bragman said.

McMahon has been in "very fruitful discussions" with the lender to resolve the situation, Bragman said.

But it's unclear whether McMahon and his wife, Pamela, will remain in the home.

The six-bedroom, five-bath house is in a hilltop gated community overlooking Mulholland Drive called The Summit, and is listed for sale at $6.25 million US. It has been on the market two years, according to real estate agent Alex Davis, who has the listing.

The house is near that of pop star Britney Spears, which doesn't always work in its favour.

"When we were trying to sell the house one time, there were about 100 paparazzi there," Davis said.