US President Donald Trump abruptly ended a televised interview with NBC's Kristen Welker after a tense exchange over his allegations of election fraud, accusing the journalist and major US news networks of being "crooked" before walking away from the conversation.

The confrontation happened during an appearance on NBC's Meet the Press, where Trump was questioned about his repeated claims that California's election system was being manipulated.

The discussion began with Trump criticising California's vote-counting process, arguing that election results were taking too long to be finalised. Referring to the state's ballot-counting timeline, the president suggested that delays were evidence of wrongdoing.

“It's four days, and they aren't even close to coming up with the (results).”

Welker challenged the assertion and asked whether he could provide proof that elections in California were being rigged. Trump did not cite any specific evidence, saying instead that his conclusions were based on observation and what he had heard from others.

As the exchange intensified, Welker noted that election officials and independent reviews have repeatedly found no widespread evidence of election fraud in the United States. Trump remained unconvinced, shifting the focus to the length of time required to certify results.

Questioning the integrity of the process, Trump argued that voters should not have to wait several days after Election Day to know the outcome of a race. Welker responded that California's system allows ballots to be processed after election day and that state officials have been working to improve efficiency.

The interview then took a personal turn.

Trump accused California election officials of corruption and extended the criticism to Welker and the media organisations covering US politics.

"They're crooked," Trump said during the exchange, before claiming that major television networks were biased and dishonest in their coverage.

Welker rejected the accusation and attempted to steer the conversation back to the original topic. Trump, however, doubled down on his criticism, claiming journalists were helping to perpetuate what he described as flawed elections.

“You're either crooked or you're stupid...You play right into their hands with this crap. You know that these elections are rigged. Your network knows that they're rigged,” the president added.

The increasingly combative interview ended moments later when Trump declared he had "had enough," signalling that the discussion was over. According to footage from the encounter, the president removed his microphone before walking away, effectively bringing the interview to an abrupt close.

Before leaving, Trump also referenced the circumstances under which the interview had been conducted, noting that he had spent significant time speaking with Welker despite poor weather conditions.