Sheryl Crow joined stars such as Beck and Stevie Nicks

The artists, who have formed a group known as the Recording Artists Coalition (Rac), call the music industry contacts "indentured servitude".

Singer-songwriter Carole King vowed: "I'm going to put a question today to the legislators, which is: why not remove the exemption?"

Henley, Rac president, said: "The record companies have been deeply involved in the legislative process for a number of years now - and we simply want a place at the table."

The late Peggy Lee fought on behalf of artists

Other stars present on Wednesday included Beck, Fleetwood Mac star Stevie Nicks and Sheryl Crow.

Their efforts to change the law follows a tentative ruling this month that record giant Universal Music should pay $4.75m (�3.3m) back royalties to up to 300 performers after a case led by the late singer Peggy Lee.

Lee, who died on Monday aged 81, claimed in a two-year court case that Universal had failed to pay her and other artists millions of dollars by under-reporting sales figures and overcharging for services.

Launching his billl earlier this month, Mr Murray said artists should take their cue from the powerful Recording Industry Association of America (RIAA) trade group and learn to lobby Congress.

"The RIAA is very effective. Rather than scoff at it, I would suggest that artists use it as a model," he told the gathering of musicians, media executives and lawmakers in Washington.

He added that it was the industry's clout that had got the amendment passed in the first place.