An investigation by Army auditors into management practices at three large Washington-area commissaries has resulted in the dismissal of eight government employes and discipinary measures against 18 others.

A source familiar with the official investigation, begun in November by a 70-member auditing team, said investigators found inventory losses totaling millions of dollars.

A report released yesterday by Rep. Dan Daniel (D-Va.) said the losses, which occurred at Cameron Station in Alexandria, Fort Myer Commissary in Arlington and Fort McNair Commissary in Southwest Washington, were in part from pilferage, erroneous cash register ring-ups, lax accounting procedures and improper handling of cash.

The auditors uncovered "a real mess-massive accounting errors and a history of bad management practices" at the three facilities, the source said.

Daniel, who requested the investigation as a member of the House Armed Services Committee, said new managers have been installed at all three commissaries since the investigation started.

Besides the eight employes fired, 10 were suspended and eight others received written reprimand, according to Pentagon officials.

The three area commissaries, which reported combined sales last year of $49 million, are military discount supermarkets. They are patronized by thousands of active-duty and retired military personnel and diplomats of countries considered friendly by the United States.

They are part of a worldwide network of such stores whose labor costs are entirely supported by a taxpayer subsidy of nearly a third of a billion dollars annually.

According to the report, "the large quantities of merchandise which moved through [the three] stores and the lack of rigid controls . . . created the potential for theft and fraud in all their imagined forms."

A final report of the auditors' findings is expected in June.

The Army audit and resulting disciplinary actions come at a time when the General Accounting Office, the congressional watchdog agency, is preparing to begin a nationwide, yearlong investigation into the operations of commissaries, military clubs, and post exchanges, which sell consumer goods.

"We'll be looking at the Defense Department's management controls in these areas," said GAO assistant director Thomas Eickmeyer. Eickmeyer said the investigation was an outgrowth of a renewed focus by GAO on fraud and abuse in government operations.

Eickmeyer said the GAO investigation will focus on "reports of fraud and abuse in the military" and management problems like those that led to the commissary audit. "We want to see what weaknesses permitted that and what corrective action the military has taken," he said.

Army officials said that as a result of the audit they have instituted a management control program to correct and prevent abuses at Army commissaries.

In an apparently unprecedented action, meanwhile, Gen. Charles E. Woods, commander of the Air Force Commissary Service, recently sent a letter to all commissary employes warning against waste and fraud in commissary operations.

"The message here is to tighten up rigidly," Woods wrote. "It is Air Force policy to deal firmly with thieves. It hasn't taken me long to observe that where we have strong management we have low losses."

According to Maj. Jules DuBois, an Air Force spokesman, Woods ordered a management survey in March of the commissaries at Bolling and Andrews Air Force Bases.

DuBois said an Air Force team uncovered "management deficiencies but no evidence of wrongdoing."

"In a supermarket it's not unusual for employes to eat a grape or something," DuBois said. "That's called 'grazing' and Gen. Woods' feeling is that grazing leads to other things. We decided to get the word out that Gen. Woods is really serious."