Fox News has announced that it will support rival news station CNN in its legal battle to restore the access of White House reporter Jim Acosta, maintaining that press credentials "should never be weaponised".

Fox, which has often been praised by US President Donald Trump, said the revoking of the CNN reporter's press pass raises concerns over freedom of the press.

"Fox News supports CNN in its legal effort to regain its White House reporter's press credential," the news channel's president Jay Wallace said in a statement.

"We intend to file an amicus brief with the US District Court.

"Secret Service passes for working White House journalists should never be weaponised.

"While we don't condone the growing antagonistic tone by both the president and the press at recent media avails, we do support a free press, access and open exchanges for the American people."

The announcement came a day after CNN -- part of the WarnerMedia division of AT&T -- said it was suing to restore the press pass of Acosta, barred after a testy exchange with Trump at a White House news conference.

Officials initially said the CNN chief White House reporter was banned for inappropriately touching a White House female intern as he struggled to hold on to a microphone and cited a video that appeared to have been manipulated.

Mr Trump later said journalists might be barred if they were not "respectful".

We need your consent to load this rte-player contentWe use rte-player to manage extra content that can set cookies on your device and collect data about your activity. Please review their details and accept them to load the content.Manage Preferences