The world’s third largest music company, EMI Group, says it and other music companies face a US investigation into how music companies influence what songs are played on the radio.

EMI says it is cooperating fully with the inquiry, which is at a preliminary stage.

New York Attorney-General, Eliot Spitzer, who has already taken on the investment banking, mutual funds and insurance sectors, has served subpoenas against Universal Music, Sony BMG, EMI and Warner Music.

Spitzer has requested information on the companies’ relationships with independent promoters, who serve as middlemen between music organisations and radio stations.

The investigation revisits an old practice of employing middlemen to sidestep US laws, restricting the bribing of broadcasters, to air particular songs without disclosing this to listeners.

EMI says it has a strict, long standing policy against unlawful radio promotion practices: “EMI has no reason to believe that there will be a material financial impact on the company.”

Clear Channel Communications, the largest US radio conglomerate with 1200 stations, said 18 months ago that it had stopped dealing with independent promoters.

Spitzer has targeted the music industry before, securing $50 million in unpaid royalties to thousands of artists such as David Bowie and Dolly Parton.