The White House has launched an all-out war on the media, vowing to fight it "tooth and nail" after a row in which Donald Trump's press secretary made allegedly false claims about the crowds at his inauguration, which were later defended as "alternative facts".

Press Secretary Sean Spicer on Monday is to hold his first daily press briefing at which he could face questions about his Saturday statement that included demonstrably false assertions about the crowd size at the inauguration and a promise by the new administration that "we're going to hold the press accountable".

Spicer made two unprovable statements in his briefing: that photographs of the audience at Trump's inaugural were intentionally framed to minimize the appearance of support, and that Trump drew the largest audience ever to witness an inauguration.

Spicer's assertion that "this was the largest audience to ever witness an inauguration - period" was widely challenged in media reports citing crowd count experts and was lampooned on social media as well.

The Washington subway system said it had 193,000 riders by 11 am (1600 GMT) on Friday, compared with 513,000 at that time during the 2009 inauguration, reported

His briefing followed Trump's visit to the Central Intelligence Agency (CIA) headquarters, where he condemned the media over underestimating the number of people who attended his inauguration ceremony and said that he had a "running war" with the media, reported New York Times.

Trump had called journalists as "the most dishonest human beings on Earth".

President Trump's chief of staff has accused the media of attempting to "delegitimize" Trump on his first days in office and vowed to "fight back" against slanted coverage.

"I'm saying there is an obsession by the media to delegitimize this president, and we are not going to sit around and let it happen," Reince Priebus said on Fox News Sunday.

"We are going to fight back tooth and nail every day and twice on Sunday."

He said there was biased media coverage about the crowd size at the inauguration and the content of Trump's address.
 

"He's ready to get to work; however, the media from Day One has been talking about delegitimising the election, talking about the Russians, talking about everything you can imagine except for the fact that we need to move this country forward."

"I'm saying there is an obsession by the media to delegitimise this President, and we are not going to sit around and let it happen," Priebus said.

"We are going to fight back tooth and nail every day and twice on Sunday."

Tensions flared anew on Sunday when Kellyanne Conway, one of Trump's top advisers, told CBC's Chuck Todd on "Meet the Press" that Spicer had merely presented "alternative facts" about the inauguration. She also accused Todd of laughing at her and said he symbolizes how Trump has been treated by the media.

Former CBS anchor Rather, who famously tangled with the Nixon White House during the Watergate era, said the situation saddened him.

"I don't think the American people as a whole, whether they supported Donald Trump ' title=' Donald Trump '>Donald Trump or not, want a situation where the press secretary to the President comes out and knowingly tells a lie," he said.