The American agency that insures the pensions of 44 million workers said its deficit more than doubled to $23.3 billion this year on the expectation additional company retirement plans will fail.

The U.S. Pension Benefit Guaranty Corp.’s deficit rose by $12.1 billion in fiscal 2004, adding to a record $11.2 billion the previous year, the agency said. The shortfall includes $11.8 billion in pension plans that the Washington-based agency said it expects to have to take over. The agency didn’t name the companies, though the head of a pension trade group said they likely include United Airlines and US Airways Group Inc.

“United and US Airways appear to be included in the number there,” said James A. Klein, president of the American Benefits Council, a Washington based group that represents pension plan sponsors. “It is a big hit. United would be the largest one ever in the PBGC’s history.”

UAL Corp.’s United Airlines, the second biggest American airline, and US Airways Group Inc., the seventh largest, told bankruptcy courts this month they want to end pension plans if the carriers can’t reach agreement with workers on changing retirement benefits. Ending United’s pensions would add $6.4 billion in agency liabilities while US Airways would add $2.1 billion.

The pension agency’s widening deficit has fueled concern that the government may need to step in as it did when America bailed out savings and loans in the 1980s and early 1990s.The Cato Institute, a free-market policy research group, said in August the agency’s shortfall may top $50 billion in the next 10 years.

“I’m very concerned about the PBGC’s health,” Senate Finance Committee Chairman Chuck Grassley, an Iowa Republican, said in a statement. “We have to do everything we can to avoid a taxpayer bailout.”

The agency, created by Congress in 1974 to guarantee pension benefits, is run by a board that includes the American secretaries of Labor, Treasury, and Commerce. Since its creation, airline and steel industries accounted for more than 70% of the claims against the program while representing less than 5% of insured participants, the PBGC said in June.

More than 1 million people are owed benefits, and the total paid in the past year topped $3 billion, the agency said today. The agency’s 2004 fiscal year ended September 30.

“The PBGC is committed to protecting pension benefits, and with $39 billion in assets, we can continue to meet our obligations,” the agency’s executive director, Bradley Belt, said in a statement. “But with more than $62 billion in liabilities it is imperative that Congress act expeditiously so that the problem doesn’t spiral out of control.”

The pension agency has said it wants authority from Congress to enforce liens in bankruptcy court on companies that miss pension payments. The agency also wants to require companies seeking bankruptcy protection to tell employees of the pension plan’s status and identify benefits that may be lost upon ending the plan.

The agency will submit its proposal to Congress next year, a spokesman, Jeffrey Speicher, said.

Mr. Klein of the Benefits Council said the $23.3 billion deficit represents payments to be made over decades. There’s time to fix the problem without a congressional bailout, he said.

“There’s more than enough money to pay benefits for the foreseeable future,” Mr. Klein said. “The longer you wait, the more severe the problem can be.” He said he expects Congress to act next year.

Stock price declines and low interest rates have eroded the value of pension plans. Workers in industries such as airlines, steel, and textiles with traditional plans that promise a set amount of benefits lost billions of dollars in pension funds as increased competition forced employers into insolvency.

Corporate bankruptcy filings reached record levels in 2001 and 2002. More than 40 American steel companies, dozens of clothing and fabric makers, and five major airlines sought protection from creditors in recent years.

Plans taken over by the pension agency in fiscal 2004 included Kaiser Aluminum Corp., which sought bankruptcy protection in 2002 to deal with asbestos-injury lawsuits, and Fleming Cos., which was the biggest grocery distributor when it sought bankruptcy protection last year, Mr. Speicher said. Kaiser is based in Houston and Fleming is based in Lewisville, Texas.

The PBGC is funded through insurance premiums collected from employers that sponsor defined-benefit plans, as well as returns on investments and the assets of pension plans that it takes over. When the PBGC seizes a pension plan, it pays up to the maximum guaranteed benefit, about $44,000 a year.