US media outlets have hit back at claims by Donald Trump that reporters lied about the size of crowds at his inauguration.

The president has warned a "big price" will be paid by those who said fewer people turned out to watch him take the oath of office than when Barack Obama was sworn in for the first time eight years ago.

White House press secretary Sean Spicer described the reports as "shameful" and said: "This was the largest audience to ever witness an inauguration - period. Both in person and around the globe."

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The comments have provoked outrage among US media outlets.

The New York Times said Mr Trump's team had made "false claims" while CNN headed their article "White House press secretary attacks media for accurately reporting inauguration crowds".

Pictures shared on social media appeared to show acres of empty space on the National Mall, where an estimated 1.8 million people stood to see Mr Trump's predecessor in 2009.

The number of journeys on Washington's Metro system on Friday also failed to match that of recent inaugurations.

As of 11am, 193,000 trips had been taken, according to the service's Twitter account.

At the same time eight years ago there had been 513,000 trips and by 11am on the day of Mr Obama's second inauguration there had been 317,000 journeys.

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Mr Trump's team has reacted fiercely to reports that the ceremony failed to draw the huge crowds expected.

"I made a speech. I looked out. The field was - it looked like a million, a million and a half people," Mr Trump said during a press conference at the CIA headquarters in Virginia on his first full day in office.

He criticised one network which reported just 250,000 people had turned up.

"That's a lie," said Mr Trump, adding: "So we caught them. And we caught them in a beauty. And I think they're going to pay a big price."

And on Sunday he hailed television ratings for the ceremony, tweeting: "Wow, television ratings just out: 31 million people watched the Inauguration, 11 million more than the very good ratings from 4 years ago!"

Mr Spicer told reporters that the area between the Capitol building and the Washington Monument, just over halfway down the National Mall, held approximately 720,000 people.

"All of this space was full when the president took the oath of office," Mr Spicer said.

He also said that white flooring, which had been used for the first time to protect the grass, had highlighted empty space in the crowd.

But the same covers were also used four years ago, it has been claimed.

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The National Park Service stopped providing crowd estimates in the 1990s, meaning the exact number of attendees may never be known.