President Donald Trump still believes millions of votes were cast illegally in last year’s election, White House press secretary Sean Spicer has said.

In the days and weeks since his election, Mr Trump has suggested that anywhere up to five million ballots were cast illegally. He has blamed these alleged illegal voters for Hillary Clinton beating him in the popular vote.

There is no evidence to support Mr Trump’s claims, which he tweeted last November, saying: “In addition to winning the Electoral College in a landslide, I won the popular vote if you deduct the millions of people who voted illegally.”

Thousands of women took to the streets on Saturday in Washington to march in protest of Donald Trump's inauguration (EPA)

On Monday night, Mr Trump reportedly returned to the issue, telling Congressional leaders that not only had up to five million people voted illegally, but that the size of the crowd who attended his inauguration last week, was bigger than that who turned out for Barack Obama in 2009. Both claims have been widely disproved.

“He didn’t change his point of view on the crowd size,” Democratic Minority Whip Congressman Steny Hoyer told CNN. “It was from his perspective a very large crowd…it was clear this was still on his mind.”

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Mr Spicer on Tuesday told reporters that Mr Trump still believed millions of votes were cast illegally. He was unable, however, to provide any evidence to support the claim.

“The President does believe that, I think he’s stated that before, and stated his concern of voter fraud and people voting illegally during the campaign and continues to maintain that belief based on studies and evidence people have brought to him,” he said.

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When he was pressed as to what evidence existed, Mr Spicer said that Mr Trump “has believed that for a while based on studies and information he has”. He said that Mr Trump was very pleased with the amount of support he had, which saw him win 33 of the 50 states in the electoral college.

Mr Trump surprised many top Republicans and Democrats in Congress on Monday when, during a dinner at the White House, he repeated his claim that millions of undocumented immigrants voted for Ms Clinton.

“I wasn’t there, but if the President of the United States is claiming that 3.5m people voted illegally, that shakes confidence in our democracy - he needs to disclose why he believes that,” said South Carolina Republican senator Lindsey Graham.