SYDNEY, Australia — Most of Australia’s newspapers, radio stations and television broadcasters are controlled by only a handful of owners, like Rupert Murdoch’s media empire, making it one of the most concentrated media markets in the developed world.

Soon, even more Australian media properties could be in fewer hands.

New legislation backed by Australia’s governing Liberal party would eliminate restrictions separating broadcast media from print and would allow media companies to own more outlets in a city. The legislation, which has cleared Australia’s Senate and could come before the lower house of Parliament as soon as next month, is widely expected to pass.

Media owners say the rules are relics of a less digital era. Like media companies around the world, Australia’s newspaper and television station owners are contending with the rise of internet companies like Facebook and Google, which are drawing away advertising dollars, eyeballs and eardrums.

But in an echo of debates raging in other countries, opponents say the changes would lead to a less diverse media market, with Mr. Murdoch’s company among those likely to benefit the most. They also contend the legislation’s backers are simply helping their political allies.