Maryland transportation officials say they are considering making an offer to buy National and Dulles International airports from the federal government in an effort to block a proposal to transfer the airports to a regional authority.

Virginia officials, who support the transfer proposal, yesterday charged that the bid statement is not serious and amounts to a "last ditch" attempt to stop the plan.

Maryland Transportation Secretary William K. Hellmann, reached at home yesterday, said that it is "too early to say" whether Maryland will place a formal bid before the U.S. Department of Transportation (DOT). He said that his department's analysts are trying to figure out a fair price for the two Northern Virginia airports.

"I don't want to make a firm commitment" that the state will bid to become sole owner of all three of the region's airports, Hellmann said. Maryland operates Baltimore-Washington International, the area's third airport.

Led by Gov. Harry Hughes, Maryland officials oppose the proposed transfer, now before Congress, saying it would bring unfair competition to BWI.

Opponents of the transfer plan say that it would not require the new regional authority to pay enough to lease the airports. The authority would pay the federal government $47 million over 35 years. Critics, including Sen. Ernest Hollings (D-S.C.), noted that the Grace Commission, President Reagan's government waste advisory group, appraised the airports at $342 million.

"It looks like $47 million is a giveaway," said Hellmann, who added that he is certain Maryland would not offer anything close to $300 million for the two airports. "I don't want to speculate now with crazy numbers," Hellmann said.

Dick Leggitt, administrative assistant to Rep. Stan Parris (R-Va.), a cosponsor of the administration's transfer bill, said the hints of a Maryland offer is "ludicrous." "It's Maryland's last gasp attempt to try to change something in the works for some time," Leggitt said.

Officials with the federal DOT, which controls National and Dulles, say it is impossible to place a fair price on large airports because they are rarely sold.

In addition, DOT officials point out that under the plan, airport land used for other than airport purposes would revert to the federal government. That provision in effect lowers the value of the two airports, DOT officials said.

But Maryland officials fear that an airport authority, by getting the airports at a low price, would reap huge profits by leasing up to 2,000 acres of Dulles's 10,000 acres to developers. They also fear an authority's development of the median strip along the Dulles Access Road. Some developers have proposed building a light rail line along the median strip from the West Falls Church Metro station to Dulles.

Profits from development could be used to build up Dulles and draw airline flights and passengers from BWI, Marylanders fear. Dulles and BWI, both underused until recent years, are competing for preeminence as the area's suburban airport of the future.

Hughes, in a recent letter to Maryland's Congressional delegation, called the administration's $47 million price "a substantial subsidy" to an authority, and warned, "All fairness in competition will vanish if this legislation is enacted.