Australia's two best-known media dynasties, the Murdochs and the Packers, have brought their considerable weight to bear on the country's proposed media reforms.

Communications minister Helen Coonan, who was hoping to unveil outline a bill for deregulation of media ownership this month, has put the plans on hold following last minute lobbying by the media mammoths.

After years of pressing for change, Packer-owned Publishing and Broadcasting and Murdoch-controlled News Limited now prefer to keep the rules as they are, their nerves jangled by the spectre of datacasting, also earmarked for liberalization.

The technology uses surplus free-to-air TV spectrum to broadcast new services - possibly foreign controlled - which PBL and News Ltd believe could pose a threat to their jointly owned pay-TV company Foxtel or the Packers' Nine Network.

Current media regulations prevent a proprietor from owning more than one newspaper, TV or radio station in any capital city. The ban on foreign investors owning more than 15% of a TV network or 25% of a major newspaper was also due to be repealed.

Data sourced from; additional content by WARC staff