US President Donald Trump’s re-election campaign says it will no longer issue press credentials to reporters working for Bloomberg News, the agency owned by Democratic presidential hopeful Michael Bloomberg.

The news agency said following Mr Bloomberg’s announcement of his presidential bid that it would no longer critically cover the Democratic presidential candidates – including Bloomberg and his rivals – but would go on covering Mr Trump.

Mr Trump’s re-election campaign made the announcement. It was not immediately clear whether the Trump White House would change how Bloomberg reporters are treated. The White House did not respond to a request for comment.

🚨🚨🚨 The Trump campaign has just banned Bloomberg News from getting event credentials. (The outlet has said that since Michael Bloomberg is running for president, it will stop investigating all Democrats — but not President Trump.) pic.twitter.com/GXF8Hk6VuB

— David Martosko (@dmartosko) December 2, 2019

Credentials enable reporters to more easily access rallies and other campaign events leading up to the November 2020 election. Members of the public must obtain tickets from the campaign and then wait in long lines to enter events.

“Since they have declared their bias openly, the Trump campaign will no longer credential representatives of Bloomberg News for rallies or other campaign events,” Mr Trump’s campaign manager Brad Parscale said in a statement on Monday.

“We will determine whether to engage with individual reporters or answer inquiries from Bloomberg News on a case-by-case basis.”

Mr Bloomberg, the former New York City mayor and billionaire media mogul who owns the eponymous news organisation, announced on November 24 that he would seek the Democratic nomination for president. Separately, he is spending $US100 million ($A147 million) of his own money on digital ads attacking Mr Trump.

In response to the Trump campaign announcement, Bloomberg News quoted editor-in-chief John Micklethwait as saying, “the accusation of bias couldn’t be further from the truth.

Michael Bloomberg. Photo: Getty

“We have covered Donald Trump fairly and in an unbiased way since he became a candidate in 2015 and will continue to do so despite the restrictions imposed by the Trump campaign.”

After Bloomberg announced his White House candidacy, Mr Micklethwait released a memo stating the news agency would “continue our tradition of not investigating Mike (and his family and foundation) and will extend the same policy to his rivals in the Democratic primaries”.

However, he said, the business-focused news organisation would continue “to investigate the Trump administration, the government of the day”.

-AAP