WASHINGTON (AP) _ The ailing Wheeling-Pittsburgh Steel Corp. has left the federal Economic Development Administration with an $85 million bill for unpaid loans that were government-guaranteed, an EDA spokeswoman said.

Nine insurance companies that issued the loans in 1980 and 1981 ''have demanded that we pay up,'' and the government will pay within 30 days, Christy Lay Bakaly of EDA said Thursday.

Wheeling-Pittsburgh filed for protection under bankruptcy laws on April 16, becoming the largest U.S. steel producer this century to file for bankruptcy court reorganization.

The company, which in 1983 was the nation's eighth-largest steelmaker, took out two loans - one for $63.5 million, the other for $36.5 million - to help finance construction of a rail mill and install pollution-control equipment, Ms. Bakaly said. The government guaranteed 90 percent of each loan. With Wheeling-Pittsburgh having repaid a portion of the obligation, the government's liability to the insurance companies is $85 million, according to Ms. Bakaly.

She said the companies are Aetna, Connecticut General, Massachusetts General, Metropolitan Life, Mutual Life, New York Life, Northwestern Mutual, Prudential and Teachers Insurance and Annuity Association of America.

The loans were part of a 1978 EDA program to guarantee up to $550 million in loans to steel companies without access to capital markets to finance modernization. The program was set up at the urging of a task force appointed by President Carter in response to layoffs in the domestic steel industry.

Wheeling-Pittsburgh spokesman Ken Maxcy said he could not comment on the loans.

Steel company failures have cost the EDA program $156.8 million, including the $85 million due under the Wheeling-Pittsburgh loan, Ms. Bakaly said. The government has been trying to recoup money by selling off the assets of Chicago's Wisconsin Steel, another participant in the loan program, she said.