A land swap considered critical to Charles County's economic growth is being held up because of a new state law meant to strengthen oversight of the transfer or sale of park and preservation land.

Sen. Thomas M. Middleton (D-Charles) is pressing the governor's office and a state board to approve the long-awaited transfer of 50 acres near the Maryland Airport in western Charles for a business park that would be anchored by a center for research and engineering of explosives.

Middleton's fellow Democrats pushed for the legislation, which will take effect July 1, after a failed plan by top aides to Gov. Robert L. Ehrlich Jr. (R) to sell 836 acres of St. Mary's County parkland to the owner of a Baltimore construction company.

Middleton said the Pomonkey transfer is different because it involves county government, not a private company or individual, and has the support of environmentalists, including the Chapman Forest Foundation.

For months, Middleton has been asking for a hearing before the Board of Public Works, the panel made up of the governor, state comptroller and state treasurer. He said Ehrlich administration officials told him that the new law has implications for the transfer.

"I can understand why the administration would be a little shaky with moving forward," Middleton said. But, he added, "there should be no caution lights on this thing at all."

Middleton formally raised the issue at a hearing of the legislature's Policy Committee last week. Shareese DeLeaver, a spokeswoman for the governor, said the Board of Public Works is waiting for official word from that committee before considering the land transfer.

"It hasn't been sent for the board's stamp of approval," she said. "The goal is to follow the letter of the law."

Sen. Brian E. Frosh (D-Montgomery), the sponsor of a constitutional amendment similar to the new law that would require legislative approval of such transfers, said it is appropriate for the Ehrlich administration to be cautious.

"If they are going to dispose of it to anybody," he said, "then the legislature ought to take a look at it."

The 50-acre parcel was promised to Charles County as part of the 1998 Chapman's Landing deal with Gov. Parris N. Glendening (D).

The centerpiece of the planned industrial park would be an energetics technology center that would serve as a training ground for engineers and a hub for research and development in explosives. The center would be a partnership between the county, the Center for Energetic Concepts Development at the University of Maryland, the College of Southern Maryland and the Naval Surface Warfare Center at Indian Head.

"That's exactly the type of industry we're trying to attract," said Marcia Keeth Stevenson, director of the Charles County Economic Development Commission. "And it would strengthen Indian Head's position as an energetics center."