Directors of Riggs National Bank met for more than three hours yesterday to discuss financier's Joe L. Allbritton's surprise bid to buy a controlling interest in their bank, but the formal meeting was adjourned -- apparently with no agreement on what the bank management will do, if anything.

One of the board's 25 members said last night that an additional meeting is planned for today -- apparently of the executive committee only -- with the formal meeting scheduled to resume on Thursday, after which he said an announcement is expected. Some directors went into yesterday's meeting in a fighting mood, seeking a way to block Allbritton's attempt to win control. Other directors were more conciliatory.

Other than an appeal to current owners not to sell their shares, about the only avenues of formal opposition to Allbritton would be a legal challenge, complaints to federal regulators or a competing bid for shares. The board also could take a neutral stance, which some analysts consider likely.

Riggs Chairman Vincent Burke Jr., who did not comment yesterday, told stockholders in a letter that they should "defer making a determination whether to accept or reject" Allbritton's offer until the board had a decision.

The bank's board membership reads like a Who's Who of Washington business and history, including Potomac Electric Power Co. Chairman W. Reid Thompson, Chesapeake & Potomac Telephone President Samuel Bonsack, Southern Railway President Harold Hall, developer Oliver T. Carr Jr. and Margaret Truman Daniel.

Directors interviewed last night all said they had agreed not to discuss board proceedings and that Burke had been designated as the only spokesman. But it was clear from the comment of several board members that opinions are divided.

At a meeting in January, 23 directors approved a resolution stating that the board wanted no one investor to own more than 15 percent of Riggs stock -- the current level of Allbritton's investment.

There was rampant speculation yesterday about the Riggs-Allbritton confrontation among investment analysts,some of whom predicted that Washingtonians are witnessing only the first chapter of a battle that could attract outside investors to open a bidding competion with Allbritton.

Meanwhile, Allbritton's offer to pay $67.50 a share for up to 600,000 shares now outstanding moves into its third day this morning, with investment firms and stock brokers predicting that the former Washington Star publisher will reach his goal and find his offer oversubscribed before the March 10 deadline.

In national over-the-counter trading yesterday, Riggs climbed $1.50 a share to a new high of $61.50 bid, but tradingremained relatively light at 10,300 shares. Trader said most owners of Riggs stock apparently wanted to sit on the sidelines and wait for potential developments, such as another bid or a Riggs defensive maneuver, before tendering their shares.

Those shares being purchased now, by investors hoping to turn them in for the higher price, have been discounted already because of the expectation that more shares will be tendered than Allbritton will take. That means that an unknown percentage of each package of shares tendered would not be accepted.

Allbritton is offering a fee of $1 a share to brokers who tender share, which analysts said will act as a strong incentive to investment firms to gather up as many as possible of their customers' shares and turn them over to Allbritton's agents.

Offering fees are not unusual in takeover situations, but Allbritton has placed no ceiling on the amount any one firm can earn in this fashion, which analysts said is unusual and indicative of the possibly unfriendly nature of the Riggs stock bid.

Allbritton's offering, which would raise his interest in the bank to 35 percent of common stock if successful, is being managed by the investment firms of Bear, Stearns & Co. and Folger Nolan Fleming Douglas Inc.

The involvement of Folger Nolan is one of many surprises in the Allbritton-Riggs story, because the investment firm and Riggs have maintained many business relationships over the years and a Folger Nolan officer sits on a Riggs advisory board. Folger Nolan officers and businesses own some 127,000 shares of Riggs common stock, but the company has pledged in the Allbritton offering not to sell any of these shares to Allbritton.

Charles Brodhead, analyst at Johnston, Lemon & Co., expressed the consensus view among investment advisors when he said of Allbritton's offering: "I think he'll get over 1 million [shares]." Brodhead said there is "no question Allbritton has the capability" of buying that many shares "but the question is, will he?"