The federal government has filed a lawsuit in U.S. District Court here against American Security Bank for approximately $290.000 concerning the manner in which the bank credited certain deposits to a Treasury Department account there.

The suit alleges that the bank did not credit numerous deposits to the account in a specified time period, during 1974.

At issue is an agreement in which ASB had offered to receive deposits directly from certain government agencies and credit them to Treasury general account, according to the suit.The bank had agreed to give same-day credit for all items received by 1 p.m. and to make efforts to credit items on the same day that came in between 1 and 4 p.m.

The suit claims that delays in crediting the account held up deposit transfers to the agency's account at the Federal Reserve Bank in Richmond, thus increasing the time before certain funds could be available to the Treasury.

A bank official said the institution's attorney has advised the facility that it "has fully adhered to the terms of the agreement," and that there would be no further comment from the bank while the suit is pending.