New York Attorney General Eliot Spitzer said Wednesday he has subpoenaed many of the nation's largest radio conglomerates in his "payola" investigation of major artists and songs that he claims got air time because of payoffs by recording companies.

Spitzer wouldn't identify the major radio companies that have been subpoenaed or release the artists and songs that he claims benefited from the pay-for-play practice for cash, trips and gifts like the scandal that rocked early Rock n' Roll in the 1950s and 1960s.

"A lot of the major songs have been implicated in this and it showed how pervasive the payola infrastructure had become," Spitzer told The Associated Press. "Probably many of the songs that were beneficiaries of the payola scheme would have succeeded without it, but certainly payola became part of the promotional structure and was integral to the game to get songs to the top. Major artists, major songs were sent up the charts through improper payments to buy spins on the air that translated into sales."

Warner Music Group Corp. (WMG) agreed last year to pay $5 million to settle its part of the investigation, and Sony BMG Music Entertainment agreed to pay $10 million.

A 1960 federal law and related state laws bar record companies from offering undisclosed financial incentives in exchange for airplay. The practice was called "payola," a contraction of "pay" and "Victrola," the old wind-up record player.

ABC News "Primetime" reported Tuesday that Spitzer is investigating the largest nine radio corporations — including ABC — in a scheme that involved Jennifer Lopez's "I'm Real" and John Mayer's song "Daughters." Songs by other artists are also being examined, including those by Jessica Simpson, Celine Dion, Maroon 5, Good Charlotte, Franz Ferdinand, Switchfoot, Michelle Branch and R.E.M., according to ABC. The radio companies that have received subpoenas control thousands of stations nationwide, including Clear Channel, Infinity which now operates as CBS Radio, Citadel, Cox, Cumulus, Pamal, and Entercom, ABC reported.

"Cox Radio has cooperated fully with Attorney General Spitzer's investigation," said Bob Neil, president and CEO of Cox, in a prepared statement. "Years before this investigation began, Cox Radio was the first radio group to terminate all relationships with independent record promoters to avoid any suggestion or appearance of `pay-for-play.' We continue to be a leader in our industry on this issue."

The other companies had no immediate comment.

In the 1950s and '60s, most payola involved direct payments of cash to DJs. Today, payola is in the form of "direct bribes" to radio programmers, including airfare, electronics, iPods, tickets to top sporting events and concerts; as well as payments to radio stations for expenses and for use in contests. Spitzer said companies had hired "independent promoters" to act as conduits for payments to radio stations and pay for "spin programs" to increase airplay of some recordings that are supposed to be based on popularity among listeners.

Spitzer said he had relied on civil laws in the payola case because the criminal laws are more specific and difficult to violate.