A formal complaint filed with New York's lobbying board asks it to investigate whether Artists Against Fracking, a group that includes Yoko Ono and other A-List celebrities, is violating the state's lobbying law, according to the document obtained by The Associated Press.

The Independent Oil & Gas Association, an industry group that supports gas drilling, filed the complaint Tuesday with the state's Joint Commission on Public Ethics.

The complaint is based on an AP story that found that Artists Against Fracking and its members, including Ono, her son Sean Lennon, actors Mark Ruffalo and Robert De Niro and others, aren't registered as lobbyists and therefore didn't disclose their spending in opposition to hydraulic fracturing, or fracking, to remove gas from underground deposits.

"The public has been unable to learn how much money is being spent on this effort, what it is being spent on, and who is funding the effort," said Brad Gill, executive director of the Independent Oil & Gas Association of New York. "I understand the power of celebrity that this organization has brought to the public discussion over natural gas development, but I do not understand why this organization is not being required to follow the state's lobbying law."

The group confirmed it filed the complaint but didn't comment further.

Artists Against Fracking, formed by Ono and Lennon, says its activities are protected as free speech. The group was created last year amid the Cuomo administration's review to determine whether to allow hydraulic fracturing to remove gas from vast underground shale formations in southern and central New York.

Gov. Andrew Cuomo continues his review as public opinion has shifted from initial support based on the promise of jobs and tax revenue from drilling in economically depressed upstate New York to mixed feelings because of concerns over potential environmental and health effects.

Seven months after Artists Against Fracking was formed, the Quinnipiac University Polling Institute on March 20 found that New York voters were for the first time opposed to fracking, 46 percent to 39 percent.

"There's no doubt the celebrities had an effect," Quinnipiac pollster Maurice Carroll said. "As far as I can tell, they made all the difference."

A spokesman for Artists Against Fracking said the group and its individual members don't have to register as lobbyists.

"As private citizens, Yoko and Sean are not required to register as lobbyists when they use their own money to express an opinion and there's also no lobbying requirement when you are engaged in a public comment period by a state agency," spokesman David Fenton said.

"If the situation changes then, of course, Artists Against Fracking will consider registering," Fenton said. "Up to now, there has been no violation because they are entitled to do this as private citizens with their own money."

On its website, the group implores readers: "Tell Governor Cuomo: Don't Frack New York." Celebrities supporting the group have led rallies and performed in the song "Don't Frack My Mother," also carried on the Internet.

Ethics commission spokesman John Milgrim didn't immediately respond to a request for comment on Friday. By law, the commission doesn't confirm or deny pending investigations.

New York's former lobbying regulator, attorney David Grandeau, said he believed the group and the supporting artists, including musicians Paul McCartney and Lady Gaga and actress Anne Hathaway, should be registered and required to disclose details on their efforts to spur public opposition to gas drilling.

"When you are advocating for the passage or defeat of legislation or proposed legislation and spend more than $5,000, you are required to register," Grandeau said Friday. "Just because you are a celebrity doesn't mean that lobbing laws don't apply to you. Your celebrity status does not protect you in Albany."

Hip-hop mogul Russell Simmons and developer Donald Trump are among the high-profile figures who clashed with the commission when Grandeau was regulator. The biggest penalty for failure to follow the lobbying law resulted in a $250,000 fine against Trump and others over casinos in 2000.