A Saudi Arabian prince has agreed to buy 15,000 shares of Financial General Bankshares, the $2.2 billion bank holding company that controls Union First National Bank of Washington and nearly a dozen Maryland and Virginia banks.

Financial General officials, however, will not identify other investors who reportedly have bought more than 15 percent of the company's stock and are trying to take it over.

At least four Financial General board members have resigned since the first of the year, in actions appartently related to a struggle for control of the company. The Washington Post learned yesterday.

The purchase of less than one percent of Financial General's stock for $187,500 by Prince Nawaf Bin Al Saud Aziz of Saudi Arabia, revealed in Federal Reserve Board documents, confirmation that Middle East interests are involved in the struggle for control of the Washington banking giant.

Finanical General has said only that "foreign bank may be seeking to obtain control" of the company, which was until last year related to International Bank, a Washington financial services firm.

International Bank (B) was forced to sell its stock in Financial General by the Federal Reserve Board, after the Fed ruled IB was illegally operating as a bank holding company.

Much of International Bank's interest in Financial General was acquired by a group of 29 investors headed by former Navy Secretary G. William Middendorf, last summer.

Disposal of other IB holdings in Financial General and dissatisfaction with Middendorf's leadership apparently set off the current struggle at the company.

Documents filed with the Federal Reserve show an International Bank subsidiary, Financial International Co., contracted to sell 15,000 shares of Financial General to Prince Nawaf.

The agreement was made Jan. 10, and the deal was to be closed March 16. Financial International is being dissolved. FTC's president, James W. Wine, could not be reached yesterday.

Prince Nawaf is one of nearly 2,000 members of the Saudi royal family. His contract to buy the shares was delivered through Hassan Youssef Yassin, director of the Saudi Arabian Information office here. Yassin, a registered agent of the Saudi government, has represented a number of prominent Saudis in the United States.

The Post also confirmed yesteray that 4 of the 21 members of Financial General's board of directors have resigned.

One, Allen Whitfield, a prominent attorney with offices in Des Moines and Washington, said he withdrew Jan. 17 as part of IB's withdrawal from ties to Ginancial General whitfield, a director for nearly 20 years, is an associate of Retired Gen. George Olmstead, head of International Bank.

Financial General confirmed that resignations had been submitted by Thomas N. Roboz and William Van Allen, both of Charlotte, N.C., and John J. Lyons.

Roboz had been nominated to represent interests of NCNB Corp., the holding company that owns North Carolina National Bank, a major southeastern financial institution.

An NCNB spokesman said the bank had sold its 80,000 shares through a broker withing the past month. "We don't know who bought it," he said.

Lyons had been recommended to the Financial General Board by Eugene J. Metzger, a Washington attorney identified on a Jone, 1977 proxy statement as the owner of nearly 88,000 shares of the company.

Neither Metzger nor Lyons could be reached for comment. Metzger was the third largest stockholder among the Middendort group, the records snow.

Financial General officials refused to discuss the sale of shares but confirmed reports that some board members have sold their stock in the company. None of Financial General's officers have sold stock, a spokesman said.

Washington real estate man B. F. Saul became chairman of Financial General only a month ago, after he and companies he controls bought about 11 percent of the shares. He was then the largest single shareholder