A political action committee formed by the Virginia Bankers Association failed to disclose at least $42,400--and possibly more than $100,000--that it contributed to state legislators' campaigns last year in apparent violation of a state elections law.

The contributions, concentrated on members of the House Corporations, Banking and Insurance Committee, were one element in an intense lobbying campaign by the bankers that recently persuaded the House of Delegates to pass a hotly contested credit card interest deregulation bill that had been stalled in committee the year before.

Despite a new state law requiring political action committees (PACs) to file with the State Board of Elections and publicly report their contributions to state candidates, the bankers ignored the requirement. State elections officials, moreover, while acknowledging that the bankers have never filed any reports on state races, say it is not their responsibility to enforce the law or even monitor compliance.

"We don't have that kind of authority," said Joan Mahan, secretary of the elections board and the state's top election official. "We weren't set up to be an investigative body."

The failure of the bankers to report their contributions--or state elections officials to take any action against them--points up the loopholes in a weak state election law that has no clear mechanism for enforcement, while disguising to a great degree the level of special interest campaign-giving to state officials.

It also helps to obscure the role campaign contributions have played in what so far has been one of the more successful lobbying campaigns of the 1982 legislative session, the bankers' effort to promote passage of a bill lifting the state's 18 percent ceiling on credit card interest rates.

"It's a joke and a deception on the people to require disclosure when disclosure isn't made and we don't have the machinery to enforce it," said Sen. Joseph V. Gartlan (D-Fairfax), a member of the committee that authored the state campaign law. "These political action committees have become the popular way for special interests to influence elections in the state, which makes it all the more important that we get a handle on them."

The role of the bankers' PAC in last year's Virginia elections can partially be seen through the campaign records filed by candidates running for the House of Delegates. They show hows that 72 candidates received at least $42,400 from the bankers' PAC, making the group one of the most lucrative sources of campaign funds for relatively low-spending legislative races. There are, however, indications that the bankers may have spent much more than that.

Many PAC contributions are funneled through political party committees, such as the House Democratic Caucus and Republican Party Caucus, which both held lavish, $100-a-ticket fund-raisers at the John Marshall Hotel this week that attracted hundreds of special-interest lobbyists. Yet under Virginia election law, this form of special interest contributions is shielded from public view since the party committees themselves are exempt from any state disclosure requirments.

A report filed by the Virginia bankers with the Federal Election Commission--a filing required by federal law if the PAC is to give to congressional candidates--shows that the group raised more than $120,000 during the past two years and made $111,140 in transfers to its state account. The federal form does not list any contributions the bankers made to legislative candidates.

Asked if the bankers' PAC actually spent $111,140 on state campaigns last year, W.O. Pearce, their Richmond lobbyist, replied: "That seems a little high." He added that not all of the transfers may have been spent and declined to respond to any other questions about the PAC.

"Our policy is that we don't talk about that with anybody," he said. "I'm not at liberty to discuss that with you."

Pearce also maintained in an interview that his group was not subject to the state law because, according to his legal advice, PAC contributions did not meet the legal definition of spending money to "influence the course of an election."

In an attempt to strengthen the election law, the Virginia General Assembly last year passed legislation that subjected the growing number of PACs in the state to the same disclosure requirements as political candidates. Under state law they must register their campaign committes with the elections board and report all contributions and expenditures over $500.

A spokesman for the state attorney general, Gerald Baliles, who interprets the law but does not enforce it, said the office could find no legal basis for Pearce's view of PAC contributions. Sen. Adelard L. Brault (D-Fairfax), who served on the committee that authored the legislation, said he was disturbed by the bankers. "I don't understand their interpretation at all," said Brault. "I think somebody should look into it."

The extent of bank contributions has taken on particular significance this session in light of the bankers' all-out lobbying campaign for the credit card bill lifting the state's 18 percent interest rate ceiling on charge accounts.

Last year, similar legislation, which labor groups have charged will "throw consumers to the wolves," failed on a 7-to-7 tie vote in the House Corporations Committee.

During last year's election, 18 of the 21 committee members running for reelection received bankers' PAC contributions ranging in size from $300 to $2,500. Two Norfolk Democrats, George Heilig and Thomas Moss, this year's corporations committee chairman, received $1,000 each.

The bankers also contributed another $2,500 to a joint "Norfolk Democrats for the House" committee that helped fund the two legislators' re-election campaigns.

Heilig and Moss had voted against the credit card bill last year, but switched their votes this year. Asked about the change, Moss said that after "talking to a lot of people," including many local bankers and Chamber of Commerce officials, he had been convinced that the Virginia banks would move their credit card operations out of state if the interest rate bill didn't pass. The PAC contributions "didn't have anything to do with it," he said.