Unidentified private investors, who are seeking to acquire a large bloc of share in Financial General Bankshares, Inc., have received an extension to Feb. 28 for making a commitment on the purchase.

On Jan. 14, International Bank of Washington, a diversified financial services firm, said the investment group had shares of Financial General, a bank holding company.

IB's block - about 22 per cent of the banking firm's outstanding shares - must be sold under a Federal Reserve Board decision. No information was disclosed on the purchase price but it has been estimated at between $13 and $15 a share.

The investment group has been organized by Harry S. Flemming and John Hanes Jr., who operate a venture capital firm in Northern Virginia. A Virginia limited partnership, Old Port Co., was formed to buy the Financial General shares.

According to an Old Port Co. letter to IB, dated Feb. 1, certain associates who had indicated a desire to participate withdrew subsequent to Jan. 14. Old Port said it believed other associates could be attracted and that the acquisition can go forward "as contemplated," provided additional time was allowed.

IB subsequently agreed to extend the commitment deadline to 5 p.m., Feb. 28, subject to a provision that IB may accept any other offer for the Financial General shares in the meantime.