The United Kingdom government department responsible for strengthening business competition and preventing anti-competitive activities has blocked 21st Century Fox's plan to buy the part of Sky it does not already own.

The Competition and Markets Authority, which is also known as the CMA, said the proposed deal was not in the public interest, because it would reduce media plurality - effectively giving Rupert Murdoch and the Murdoch Family Trust too much control over news providers in the UK and, by extension, public opinion.

Fox currently owns 39 percent of UK broadcaster Sky. In 2016, Fox offered 11.7 billion pounds ($16.3 billion) for the remaining 61 percent, triggering the CMA probe.

The CMA's finding was provisional, so the parties to the proposed deal can fine-tune and resubmit it.

Sky said it was "disappointed" with the report but "had set out possible remedies" and would be "seeking submissions on these".

"We will continue to engage with the CMA ahead of the publication of its final report in May," said a statement from the company.

The Guardian reported that possible remedies to address the CMA's concerns around media plurality might include Sky News being spun off, or being insulated from potential influence from the Murdoch family.

To make matters more complicated, Disney is in the process of buying most of Fox's business. That proposed takeover still needs approval from regulators in the United States and was not considered by the CMA.

At the moment, the Murdoch Family Trust controls several media platforms in the UK - TV and radio stations, online providers, and newspapers - and its content is consumed by around one-third of the UK population.

The BBC quoted Anne Lambert, chairwoman of the CMA's independent investigation group, as saying: "Media plurality goes to the heart of our democratic process. It is very important that no group or individual should have too much control of our news media or too much power to affect the political agenda."

The CMA's final report will be submitted to the UK's culture secretary in May for a final decision.

The Telegraph reported that the regulator's provisional ruling is unlikely to affect Disney's plan to buy Fox for 49 billion pounds.