Virginia Rep. Dan Daniel, the state's senior Democratic member of Congress, acknowledged yesterday that he had billed the federal government for automobile travel when he had flown to his district for free in airplanes provided by a defense contractor.

The House ethics committee, which is already probing Daniel's previously disclosed acceptance of 23 airplane trips from a defense contractor, has broadened its investigation into whether Daniel may have made false billings for government money by submitting vouchers for car travel he did not make, according to sources.

The expanded investigation may increase problems for Daniel, 71, a senior member of the House Armed Services Committee. A southern conservative and former textile executive, Daniel has spent most of his 17 years on Capitol Hill far from controversy.

Daniel said in a statement yesterday that his wife, Ruby, usually drove his car to their home in Danville -- about 250 miles from Washington -- because it was needed there, and that he billed the government for that use of the automobile.

"On many occasions, when I flew in this manner, Mrs. Daniel drove the car to or from Washington, as it is needed at both destinations," he said. "I had assumed that mileage was paid on the use of the automobile, irrespective of who drove it, so long as it was in the performance of my official duties."

Daniel said that the ethics committee learned of the car voucher billings from his attorneys and at his request. He said his attorneys told the panel of "the matter of getting my car to and from the home district."

" . . . I offered to reimburse the House for these trips, if not allowed under the rules, and have awaited a determination by the committee as to the matter of propriety," he said.

The ethics committee refused to comment yesterday on the progress of the investigation, which it began earlier this fall after Daniel confirmed in a floor speech that he had taken 23 free airplane rides from Beech Aicraft Corp., a defense contractor, while urging Congress to direct the Pentagon to buy 24 Beech C12 airplanes for the military.

Daniel, who was in his southern Virginia district yesterday but was not available for an interview, said in the statement that he has heard nothing about any committee determination. House ethics rules prohibit members of Congress from accepting more than $100 a year in gifts, including transportation, from companies with an interest in legislation before Congress.

In his emotional House speech in September, Daniel said he misunderstood the House's rules and had sent Beech a check for $1,127 to pay for the flights. He said in interviews then that he was not involved in a conflict of interest, and that the free flights had not influenced his support of the airplane.

He said that he had learned of the value of the planes while a textile executive and that he believed they were needed by the military brass to go around the country to check on the status of reserve and National Guard training.

Sen. Strom Thurmond (R-S.C.), a member of the Senate Armed Services Committee, acknowledged in October that he had also accepted free transportation from Beech, in violation of Senate rules. He said he sent the company a check for $5,669 for 18 free flights. House Speaker Thomas P. O'Neill Jr. also acknowledged accepting a free flight from Beech to Hyannis, Mass., and a spokesman said he would repay the company.

Before the controversy over the plane rides, Daniel had spoken of retiring at the end of this term. But he said he is now leaning toward running for reelection. "I won't be hounded out of office," he has told his Virginia colleagues.

Daniel's ethics committee troubles come at a time when he has attained more influence on defense issues than he has had.

As chairman of Armed Services' readiness subcommittee, Daniel has been instrumental in an attempt to establish a defense special operations agency that would take over control of the special forces from the various services.

Under Daniel's plan, the Army's Green Berets and Delta Force, the Navy's Seals, and other special forces would be put under a single civilian command to gear up to fight terrorism and "low-intensity" operations such as the Grenada invasion