THE Sydney talkback radio station 2GB - home to presenters Alan Jones and Ray Hadley - has failed in its bid to stop new rules that force it to reveal its advertising backers on air, despite a plea that it would be tantamount to an attack on freedom of speech.

The station's owner, Macquarie Radio Network, argued it would be impossible to comply with the new rules, which say presenters must declare if they or their radio station are getting cash or favours from a sponsor.

Macquarie had sought an injunction to stop the introduction next Tuesday of the new rules, which the Australian Communications and Media Authority rewrote to prevent another cash-for-comment scandal.

Macquarie's counsel Tom Blackburn, SC, said that it was impossible for the station to comply with disclosure rules because on any given day 2GB had between 100 and 300 ads and it could not expect producers to be aware of all deals in place to spruik products or services on air. The constant disclosure would also stymie the flow of interviews, and ultimately threaten freedom of speech, Mr Blackburn told the federal court.

"It's one thing for a regime of disclosure of agreements but quite another to impose a requirement that compels a broadcaster to repeatedly interrupt a politician with disclosures,'' Mr Blackburn QC told the Federal Court. "That's a real and pointless effect on our freedom to communicate on matters of government.''

The court heard that Macquarie would have to employ "an army of new people'' to comply, and failure to disclose a deal could land it with a civil action, criminal proceedings and possible loss of licence.

Justice John Griffiths rejected Macquarie's bid to stay the start of the statutory rules, noting the company could have acted sooner and that given the rules were posted on legislative register the public expected them to come into force.

The two parties are back in court in late May when Macquarie and 2GB renew their challenge to the validity of the new commercial radio standards.