Donald Trump has accused protesters who took to the streets of cities across the US to demand he publish his tax returns of being part of an organised conspiracy paid for by persons unknown.

The billionaire said his election as President had made the release of his tax details irrelevant, writing on Twitter: “Someone should look into who paid for the small organised rallies yesterday. The election is over!

"I did what was an almost an impossible thing to do for a Republican – easily won the Electoral College! Now tax returns are brought up again?" he added, highlighting the issue to his 28 million followers.

Recent polls show 74 per cent of Americans want Mr Trump to release his tax returns. Every president since Richard Nixon has made theirs publicly available, but Mr Trump has repeatedly refused to do so.

Dozens of demonstrations took place yesterday, including in Washington DC, New York and south Florida, where protesters marched to the President's Mar-a-Lago resort – where he is currently staying.

Many featured oversized inflatable chickens with the President's features, suggesting Mr Trump is too afraid to make details of his tax affairs public.

In the US, 15 April is colloquially known as Tax Day, as it's usually the day on which individual tax returns are due.

"We're like your taxes. Unpaid," wrote one Twitter user in response to the President's comments, while another wrote: "'Small' was your pathetic inauguration crowd"

As a candidate and as president, Mr Trump has steadfastly refused to release his tax returns, citing an ongoing audit by the Internal Revenue Service (IRS).

Mike Stutz dressed as a Russian general stands beside a giant Trump chicken as he joins protesters taking part in the 'Tax March' in Los Angeles, California (Getty) (Getty Images)

In September, he told ABC News: “I don't think anybody cares, except some members of the press.”

However, the IRS has said that the President can release his tax returns even while under audit, with critics raising questions about what his tax returns say about his net worth and various business ties.

Mr Trump has previously claimed protesters at his rallies, and at Republican town hall meetings, were paid.

Last month, two pages of the President's 2005 tax return were obtained by investigative reporter David Cay Johnston and published by the site DCReport.org.