Bingo has become a $50 million-a-year industry in Virginia, the chairman of a General Assembly subcommittee estimated yesterday as the panel began a search for ways to tighten regulation of the state's principal form of legalized gambling.

Sen. Wiley F. Mitchell Jr. (R-Alexandria), a member of the subcommittee said as the hearings opened that operations have become so large, the Assembly may find it necessary to set up an agency similar to the Alcoholic Beverage Control Commission to provide uniform regulation of bingo games.

Legislators and law enforcement officers throughout the state have condemned the current bingo law as vague and difficult to enforce. In Alexandria, apparent reluctance to enforce the law by Commonwealth's Attorney William L. Cowhig has led to the appointment of a special state bingo prosecutor and to a federal grand jury investigation. The federal panel also is investigating massage parlor operations.

The $50-million-a-year estimate for bingo operations in Virginia was made by Del. Ralph L. Axselle (D-Henrico) on the basis of a statewide survey by the staff of the Joint General Laws Subcommittee on Bingo.

The subcommittee yesterday heard pleas from organizations such as a bingo regulations and conflicting please from organizations such as a Lion Club and an association for retarded children to revise the law to insure continuation of their bingo operations.

Richmond Commonwealth's Attorney Aubrey Davis, who estimated Richmond games gross $2.5 million to $3 million a year, called for more uniform and frequent reports of game receipts by organizations operating them.

"I'm realistic enough to say that bingo is here to stay and we've just got to live with it," Davis said. "We can't kid ourselves. This is a big business and we have to have uniformly of regulations to prevent crime in connection with bingo."

Several witnesses testified that the organizations they represent end up with only a small portion of game receipts for charity partly because bingo competition is forcing up jackpot sizes.

Ray Shepherd, president of a Richmond area Lions Club, asked the lawmakers to limit competition by making sure organizations give bingo receipts away rather than use them for their own purposes.

He said his Lions Club was forced to guarantee a grand jackpot of $500 at its weekly games in addition to regular game prizes in order to attract a crowd large enough to net about $200 weekly for club charities.