Virginia and Maryland officials split yesterday on a central element of the proposal to transfer control of Dulles International and National airports: the size of the airports' price tag.

In a hearing before the Senate Governmental Affairs subcommittee on governmental efficiency and the District of Columbia, chaired by Sen. Charles McC. Mathias Jr. (R-Md.), Maryland officials contended the plan to turn over the airports to a regional authority for $47 million amounted to a giveaway that would tilt competition away from Baltimore-Washington International Airport.

"The major item of contention is price, as far as we're concerned," said Maryland Transportation Secretary William Hellmann. He argued that the low transfer price "would give National and Dulles the opportunity to build facilities faster and to keep landing rates low, which would create unfair competition for BWI."

The proposal by Transportation Secretary Elizabeth H. Dole to transfer the airports, the only two in the country now under federal control, would lease National and Dulles to an 11-member regional authority for 35 years, then transfer the ownership permanently.

According to the legislation, the new authority would pay the government $47 million, at a 4.9 percent interest rate, over that time. That figure is the federal government's "hypothetical debt," the amount it has invested in the airports over the years but has not recouped in revenue.

Yesterday Hellmann and Sen. Paul S. Sarbanes (D-Md.) argued that the $47 million payment, which they said is much lower than the airports' market value, would permit improvements that could draw airlines and passengers away from BWI.

But Virginia and federal officials, who support the transfer, stressed the airports' market values are irrelevant in a transaction that is not intended to be a sale.

"We're not selling airports," but transferring their management, former Virginia governor Linwood Holton told the subcommittee. Holton headed the commission that recommended the airport transfer after a year's study.

The question of the airports' worth is further complicated by restrictions on what the new authority could do with the properties.

According to the bill, the properties must continue to be used for "airport purposes," a requirement that could affect their value, explained Oliver W. Krueger, a senior associate director of the General Accounting Office.

Maryland officials pointed to the Grace Commission's 1983 estimate of the two airports' value at $341.5 million. That estimate, based partly on a 1972 appraisal of the airports' worth adjusted for inflation, has been criticized by Virginia and federal officials.

Holton said the $341.5 million figure might be accurate if the new authority were able to build condominiums on the properties or develop them for other purposes. But because their use is restricted, the actual value is much lower, he said.

A hearing on the transfer bill before the Senate Commerce Committee is scheduled for this morning.