But former prime minister Paul Keating has described the competition watchdog giving the merger the green light as a “truly appalling decision” which will “poison quality journalism”.

The Australian Competition and Consumer Commission ruled today the $4 billion merger could go ahead.

Fairfax head Greg Hywood told staff soon after the approval would allow the process to be officially completed by December 10.

“The planning and preparation to bring Fairfax and Nine together as one great media company is well under way,” Hywood wrote to Fairfax workers in a letter.

Nine has put the date a touch earlier at December 7, but both deadlines depend on the merger successfully passing a series of final hurdles.

They include the proposal’s approval by Fairfax shareholders at a November 19 meeting and court approval on November 27.

“The directors of Fairfax unanimously recommend that Fairfax shareholders vote in favour of the scheme, in the absence of a superior proposal,” Nine said in a statement today.

The Australian Competition and Consumer Commission examined more than 1000 submissions as well as documents demanded from Nine and Fairfax before giving the merger the green light.

The authority said the move will likely reduce competition in the Australian news content market – but not enough to break the law.

But Keating said the ACCC’s call had consigned key Fairfax mastheads to the “ethical dustbin of Channel Nine”.

“What the ACCC has done today is effectively skewer major source media diversity in Australia,” the former Labor leader said in a statement,

“A low-rent, news organisation, Channel Nine, will have editorial command of the major print mastheads in the country.

“This will poison quality journalism; but more than that, remove chunks of local specific political issues, normally covered by newspapers, from the political debate.”

The merger comes after media ownership laws were changed in October 2017, allowing a proprietor to control more than two-out-of-three platforms – TV, radio or newspaper – in one licensed market.

Keating said those laws has protected capital city print journalism from domination by television companies for 32 years.

After Nine and Fairfax proposed the step in July, Communications Minister Mitch Fifield said the law changes had been necessary to give media organisations the best chance of survival.

“The greatest threat to Australian media diversity would be the failure of an Australian media organisation,” he said.

Labor communications Michelle Rowland said in September the merger meant the media was about to get “a whole lot more concentrated”.

The union representing journalists, the MEAA, condemned the ACCC’s decision today, describing it as a “body-blow to media diversity, and the forerunner to future mega-deals that will reduce coverage of matters of public and national interest and do untold harm to media jobs”.

MEAA chief executive Paul Murphy said the merger was the inevitable result of the removal of the two-out-of-three media ownership rule.

“The ACCC seems to have neither the will nor the regulatory tools to block transactions like this,” Murphy said.

“As we saw with the 2011 merger to form Seven West Media, media mergers of scale result in endless cost-cutting to increase ‘synergies’, far fewer journalists and far less local and national public interest journalism, while also wiping billions of dollars of value from the company.

“The likely outcome of Nine’s takeover of Fairfax will be the same.

– with AAP