The Securities and Exchange Commission has charged a Riggs National Bank director with violating federal securities laws in the stock sale that began the takeover fight between millionaire Joe L. Allbritton and the bank's management.

According to sources, the SEC charges that Jorge Carnicero took unfair advantage of knowledge that Allbritton was willing to pay a premium price of %67.50 for the stock, information gained during negotiations with Allbritton. When those talks were going on last fall, Riggs stock was selling in the 40s.

Before Carnicero closed the sale, he and two friends purchased additional stock to sell to Allbritton at a profit of more than $100,000, according to a description of the charges.

At the time he did so, Carnicero, as a director of the bank, had a legal responsibility to other shareholders to disclose information that might increase the value of the bank's stock, according to a description of the SEC charges. Instead, according to the charges, he used the information to benefit himself and two friends -- an assistant, whose name could not be ascertained, and a man from New York.

The charges against Carnicero are not expected to have an impact on the takeover fight, since they reflect neither on the bank nor Allbritton.

Carnicero, who is chairman of Dynalectron, a McLean aviation and electronics firm, said in a statement issued last night that he and Fin-America, a company also charged in the SEC complaint, had attempted to persuade the SEC that its interpretation of the facts was an unwarranted extension of present laws. That attempt was unsuccessful.

The statement said that Carnicero and Fin-America, "without admitting or denying the facts alleged in the complaint, entered into consent orders in order to avoid protracted and expensive litigation which would have created substantial distractions from ongoing endeavors." Sources close to the case said the consent orders, which must be approved by a federal judge, would require Carnicero to repay money he made on the stock sale.

Carnicero also said in the statement that the decision to enter into the consent orders without admitting or denying the facts was influenced by his desire not to complicate further the current situation involving Riggs National Bank.

According to a description of the SEC case, Carnicero and his two friends bought an additional 6,900 shares to sell to Allbritton as part of the Carnicero block. When Allbritton acquired the Carnicero block of 386,645 shares in January, he became the bank's largest shareholder, with approximately 15 percent of the stock of the city's largest financial institution.

A few weeks later, Allbritton announced a plan to buy at least 600,000 more shares of Riggs stock at the same price. That offer is now the center of a fierce fight between the former Washington Star owner and Riggs management over control of the bank. If Allbritton succeeds in buying that much more stock, he will control approximately 35 percent of the bank's shares. Right now he is temporarily barred by a court order from acquiring the stock.

According to sources, if the settlement is approved by U.S. District Court Judge Norma H. Johnson, Carnicero will be required to repay profits made from his trading. Carnicero and his two friends made approximately $135,000 on their purchases. That figure also includes some money that would be owned to Riggs under securities laws covering short-swing profits.

The SEC charges, which were apparently filed last Friday night, name both Carnicero and Fin-America Corp., a company controlled by him through which he owned some Riggs stock. Carnicero's friends were not charged, apparently because they acted as individuals not encumbered by the legal restraints on directors.

According to papers, Allbritton has filed in court, Riggs' board of directors passed a resolution Jan. 13, when Allbritton was on the brink of acquiring Carnicero's stock and had made it clear he might buy additional shares, stating that it was against the best interests of the bank for any person to own more than approximately 15 percent of its stock.

Before that, Allbritton has said, his interest in the bank had been warmly welcomed by Riggs' management.

Although Allbritton and Carnicero postponed the scheduled closing on their stock transaction, Allbritton ultimately went ahead with it because he was faced with the loss of $1.3 million under the terms of an option agreement if he failed to purchase the Carnicero block.