Perpetual American Federal Savings and Loan Association of McLean is considering a merger proposal that would give it control of Interstate Federal Savings and Loan Association, the District's third-largest S&L.

Perpetual already is the biggest S&L in the area, and a merger with Interstate would be the McLean S&L's third in just over a year.

Industry sources say the two associations already have signed an agreement to merge, but those reports were denied unequivocally yesterday by Perpetual American Chairman Thomas J. Owen, who confirmed that discussions are being held.

"We're talking, and that's about it," Owen said. "It's at the what-if stage."

Officials at Interstate could not be reached for comment yesterday.

Although Owen declined to be specific about his discussions with Interstate officials, he acknowledged that the merger talks have "gone a little further than most." He added, "We will continue talking until we agree to disagree."

In the meantime, except for some last-minute hitch, very little appears to stand in the way of an agreement between the two S&Ls.

"There is something in it for each of us," Owen said. "We both have strong net worths, and our board can work with their board."

Interstate was set to merge with Home Federal Savings and Loan of the District last year, but a last-minute disagreement over a proposed reassignment of key personnel forced the parties to break off talks.

Perpetual American has assets totaling $2.2 billion, and Interstate has about $500 million. Although combining the assets of the two institutions would solidify Perpetual American's position as the biggest S&L in the region, a more important factor in a merger would be its total market coverage.

Originally a District S&L, Perpetual American changed its charter and moved its headquarters to Northern Virginia after receiving approval last June to acquire Washington-Lee Federal Savings and Loan Association of McLean. Less than a month later, the Federal Home Loan Bank Board approved a merger of Guardian Federal Savings and Loan Association of Silver Spring into Perpetual American.

As a result of those two mergers, Perpetual American can open branches anywhere in Virginia and Maryland or merge with other S&Ls in those states. It has the same options in the District, where it maintains several offices.