Washington Bancorp, owner of the District's third-largest bank, is discussing with federal regulators the possibility of taking over one or more state-chartered Maryland savings institutions.

Senior Vice President Patrick G. Hartley said bank officials had approached the Federal Home Loan Bank Board several months ago to discuss an acquisition without revealing the name of the target. The thrift or thrifts would be chosen from among those that were privately insured by the Maryland Savings Share Insurance Corp. until it was replaced by the State of Maryland Deposit Insurance Fund this spring.

The regulators told Washington Bancorp that their policy is not to let out-of-state holding companies buy healthy thrifts without also taking on an ailing institution. Hartley said yesterday the discussions are "progressing, but it is uncertain as to a final result."

Washington Bancorp officials have ruled out Old Court Savings and Loan and Merritt Commercial Savings and Loan, the two worst cases, as being too costly. But there are alternatives. Of the 102 state-chartered thrifts formerly insured by MSSIC, just 20 have qualified for federal insurance. Another 12 have received conditional approval, meaning they have filed plans to bring their capital-to-liabilities ratios up to the 5 percent federal requirement.

Gov. Harry Hughes has lifted restrictions on 45 others and placed them under the state's protection after federal examiners found them to be sound operations. That leaves 25 thrifts that have thus far been unable to qualify for federal insurance.

Two of these, Friendship Savings and Loan and Chesapeake Savings and Loan, already have been targeted by Chase Manhattan Corp. One other has been reported to have requested a conservatorship. A dozen of the remaining thrifts are under $40 million in asset size.

Acquiring a savings institution in Maryland fits in with $1.3 billion Washington Bancorp.'s strategic objectives to explore potential opportunities in the area, said Hartley.

Neither of the two largest bank-holding companies in the District, Riggs National Corp. and American Security Corp., is known to be interested in acquiring ailing Maryland thrifts. First American Bankshares already owns a bank in Maryland.

An article Wednesday on the acquisition of Friendship Savings and Loan by Chase Manhattan Corp. incorrectly identified another Maryland savings and loan association purchased by Chase Manhattan Corp. Chase purchased Chesapeake Savings and Loan of Annapolis prior to the Friendship acquisition.