THE FBI is investigating allegatins that Boss & Phelps Inc., a District of Columbia real estate company, may have engaged in "check-kiting" activities tht two of Washington's leading banks claimed cost them about $1 million.

The allegations against Boss & Phelps, a 74-year-old real estate company with a respected reputation, were made by the National Bank of Washington and First American Bank, N.A., of Washington, according to sources familiar with the probe.

Preliminary bank figures submitted to investigators indicate that NBWclaimed losses of about $600,000 and First American claimed between $300,000 and $400,000, sources said.

An FBI spokesman confirmed yesterday that Boss & Phelps is under investigation. "We're working on a [loss] figure of about $1 million," the spokesman said. Subpeonas has been issued by the U.S. Attorney's office here for records relating to the Boss & Phelps checks under scrutiny.

No charges have been filed in the matter.

"We deny any allegations of wrongdoing," said Brian C. Shevlin, an attorney for the company and its two principal owners, Owen N. ycummins and Edward B. Ballow Jr. Shelvin said the company "by no means" accepts the loss figures being claimed by the two banks. The company, which has offices in Washington at 3830 Veazey St. NW and 4211 39th St. NW, and in Vienna, is continuing to operate, Shelvin said.

Officials at both banks declined comment on the probe yesterday. An official at one of the banks, who asked not to be identified, said banks traditionally have reserve amounts to cover such claimed losses.

The investigation began after a third bank, Riggs National, reportedly refused to honor Boss & Phelps' checks when they were presented for payment by First American and NBW. Boss & Phelps maintains accounts at all three banks. Riggs has not reported any losses.

Check-kiting is a scheme in which checks are floated bwtween tow or more banks so that money is obtained before the banks realize there were insufficient funds to cover the checks. The check writer takes advantage of a time lapse before banks can verify that a check drawn on an account on an account at another bank is adequately covered.