US news organisations have rebuked Donald Trump after he falsely claimed on live television that he had won re-election even as votes were still being counted.

With reporters and supporters gathered at the White House, the president said it was “a major fraud on our nation” that he had not been declared the winner, adding: “As far as I’m concerned, we already have won this.”

The words were barely out of his mouth before television anchors rushed to refute his claim.

CBS News’s Norah O’Donnell said Mr Trump was “castrating the facts” by “falsely claiming that he has won the election and disenfranchising millions of voters whose ballots have not been counted”.

“Donald Trump is losing right now both in the popular vote and the electoral vote and there are many states left to be called,” ABC News’s George Stephanopoulos said.

Savannah Guthrie of NBC News said: “The fact of the matter is we don’t know who won the election.” She had interrupted Mr Trump’s speech to tell viewers that several of his statements were not true.

The Associated Press said that at the time of Mr Trump’s statement that its count had him winning 213 electoral votes to Democrat Joe Biden’s 225. The AP has determined it is too early to declare a winner in several states, including Pennsylvania, Georgia and Michigan.

It was an explosive moment after a frazzled nation had sat through hours of uncertainty. Media outlets had warned for weeks that Americans would have to be patient waiting for a decision in the bitter campaign, and repeatedly drove that point home through their election night coverage.

Mr Biden had spoken to supporters in Delaware, expressing confidence in his campaign and saying he wanted to see every vote counted.

“Keep the faith, guys, we’re going to win this,” he said.

Mr Trump immediately responded with a tweet saying “we are up BIG, but they are trying to STEAL the election. We will never let them do it”.

“This is an extremely flammable situation and the president just threw a match into it,” said Chris Wallace on Fox News, which is normally a Trump-friendly channel.

His Fox colleague, former George W Bush administration aide Dana Perino, said: “He just went a step too far.”

Conservative commentator Ben Shapiro tweeted that it was “deeply irresponsible” for Mr Trump to claim victory.

The president’s team was angry at Fox News Channel for striking out ahead of other news organisations in declaring that Mr Biden had defeated Mr Trump in the battleground state of Arizona.

It would have been the first state to flip parties from 2016, and was crucial in the path to 270 electoral votes and victory.

Fox’s decision desk chief Arnon Mishkin said Mr Trump would not be able to catch up to the Democrat’s lead in Arizona, adding: “I’m sorry, but we’re not wrong in this particular case.”