NEW YORK: Experts and elected officials on Monday debunked Donald Trump’s claim that “millions” of Americans voted illegally on Election Day, as the president-elect railed against ballot recount efforts spearheaded by the Green Party.

Cloistered in his Florida resort for the long Thanksgiving weekend, the 70-year-old maverick tycoon who has never previously held elected office took to Twitter to indulge in one of his customary tweet storms.

On Sunday, before he boarded his private jet back to New York to resume meetings with potential cabinet picks, he claimed he would have won the popular vote if it were not for “the millions of people who voted illegally.” “Serious voter fraud in Virginia, New Hampshire and California — so why isn’t the media reporting on this? Serious bias — big problem!” he followed up later.

His outburst came as steps were being taken towards recounting votes in three swing states which Trump won: Wisconsin, Pennsylvania and Michigan.

But no election observers believe there was widespread fraud and few expect recounts to change the outcome of the vote, which former secretary of state Clinton conceded to Trump in an early-hours phone call on Nov 9.

Experts and elected officials fell over themselves on Monday to dismiss Trump’s claims as totally unsubstantiated and said they set a dangerous precedent by potentially undermining trust in democracy or confidence in his leadership.

“I think it’s a claim that’s completely unsubstantiated,” said Costas Panagopoulos, director of the Elections and Campaign Management program at Fordham University.

“I think he’s trying to plant a seed of doubt in the American public to negate against the things advanced on the other side of the aisle about potential irregularities or even fraud that are the basis for the recounts,” he added.

Trump spent weeks during the campaign warning that the result might be “rigged” and is now — with his aides — pushing back hard against proposed recounts.

Green Party candidate Jill Stein, who received 1.1 per cent of the vote in Wisconsin, has requested a recount in the state. Trump won 47.9 per cent and Clinton, the former secretary of state, won 46.9 per cent of the Wisconsin vote.

Clinton’s campaign has said it would join the process and the dispute roils what is already been a rough transition period, with Trump in back-to-back meetings with people he is considering for cabinet.

On Monday, he also threatened to end the thaw in diplomatic relations with Cuba, following the death of Fidel Castro, unless Havana makes concessions on human rights and opening up its economy.