Prince George's County Executive Parris Glendening said yesterday that there has been no preferential treatment for developers in county land transactions and added that he will take steps to ensure there is no "appearance of impropriety" in future land sales.

In an interview, Glendening said he will undertake a broad review of county land sales to make certain the county does not deprive itself of taxes when it negotiates with private developers.

Glendening, commenting on a land swap the county made last year, said that he instructed his staff to "find a piece of land to trade" to appease a developer who had sued the county for banning development in a highway median.

But Glendening said that in retrospect, he believes certain aspects of the 1989 transaction -- in which the county swapped a $1.1 million Fort Washington commercial site for a $300,000 strip of Bowie highway median -- could have been better handled by his senior aides. The swap allowed developer Robert W. Douglas Jr., of College Park, to save an undetermined amount in federal tax and at least $19,480 in county and state property transfer taxes.

"Was this the best deal that we could get?" Glendening asked. "Clearly, the county wants as much tax revenue as possible. We were in a situation where you're darned if you do and darned if you don't."

Glendening said questions about the land swap demonstrated the need for greater public input into county land transactions. He did not provide any specifics on what his review would entail or what changes in procedure he might recommend.

Glendening said he did not negotiate details of the transaction with Douglas but was briefed on its progress by Fern Piret, who was then his senior adviser and is now the county's planning director.

Glendening's comments were the first acknowledgment of his role in the 1989 land swap with Douglas, a transaction investigated by a Prince George's County grand jury. The grand jury returned no indictments, but jury members say they were deeply disturbed by the swap and were hopeful that prosecutors would pursue the matter with trained criminal investigators.

Although both county and state prosecutors declined to further probe the matter, U.S. Attorney Breckinridge L. Willcox in Baltimore is reviewing materials on the swap and examining tax questions raised by the transaction, according to law enforcement sources.

The sources said the review has not reached the stage of a formal investigation. County Attorney Michael Whalen said yesterday that no documents have been subpoenaed but that the county will cooperate.

Glendening said he left details of the land swap to "trained professionals" on his staff and was unaware that his office agreed to undervalue the county's property so that Douglas could save federal income and county and state property transfer taxes.

County Administrator John Davey signed an agreement with Douglas in which the county agreed to place the value of its own property -- which had recently been appraised at $3.2 million -- at $300,000 so Douglas could report the transaction as a tax-free exchange.

Internal Revenue Service experts say that transactions do not qualify as tax-free exchanges unless the owners have held property for some time for investment or business purposes. County officials say that Douglas exercised his option to buy the median property for $300,000 the same day that the county signed papers finalizing the trade.

Douglas has declined to comment, but his attorney, William Knight, has said there is nothing illegal about the transaction.

Willcox's office also is reviewing materials gathered by a private citizen, lawyer James Casey, on the county's sale of properties in the Collington Center on Route 301 near Upper Marlboro.

Casey, who has a suit pending against the county over development rights to land he owns along Route 301, has alleged that the county sold land at bargain prices to chosen developers, many of whom contributed to Glendening's campaign.

Glendening yesterday dismissed the allegations as "outrageous and completely unfounded."