Trump's treasury secretary 'breaks law' by refusing to hand over president's tax returns for investigation

'There is no wiggle room in this, it is the law,' former federal prosecutor says

Related: Trump 'will never release tax returns' claims White House official Mick Mulvaney (Getty)

The Trump administration has been accused of breaking the law after the US treasury secretary refused to provide Congress with the president’s tax returns.

In the latest stand-off between the US government and Democrats on Capitol Hill, Steven Mnuchin said on Monday he was turning down the request from the Ways and Means Committee as it lacked a “legitimate legislative purpose”.

“Out of respect for the deadlines previously set by the committee, and consistent with our commitment to a prompt response, I am informing you now that the department may not lawfully fulfil the committee’s request,” he wrote in a letter to the panel.

A number of experts said Mr Mnuchin was violating the law by ignoring the request by Democratic congressman Richard Neal, chair of the committee in the House of Representatives.

“The law is clear that the IRS must turn over tax returns requested by the House Ways and Means Committee, which has many legitimate and important reasons to request the president’s returns,” said Noah Bookbinder, a former federal prosecutor and chief of government watchdog Citzens for Responsibility and Ethics in Washington.

He added: “There is no wiggle room in this, it is the law. Secretary Mnuchin says he has decided not to turn them over, but that is not a decision that is his to make. Congress cannot accept this.”

Democrats have long sought to obtain a copy of Donald Trump’s tax returns, in the belief it may provide evidence of unethical behaviour in the way he has operated his finances and his businesses both before and after entering the White House.

Though there is no law saying presidents must release their tax returns, Mr Trump remains an exception among US leaders in recent history by refusing to do so.

Mr Neal requested the document on the basis of a law which says the Internal Revenue Service (IRS) “shall furnish” the returns of any taxpayer to a handful of senior legislators, among them the chair of the Ways and Means Committee.

“The law here is exceptionally clear and says that Mnuchin ‘shall’ provide the tax returns to the Chair of House Ways and Means,” tweeted Joyce Alene, a law professor at the University of Alabama. “There’s nothing that permits him to consider the reasons the Chair made the request.”

Richard Painter, a former White House ethics chief under George W Bush, tweeted: “The House should hold Mnuchin in contempt.”

The expectation now is that the issue will be further spun out by means of a legal tussle. Democrats could seek to subpoena the IRS for the president’s tax returns or to file a lawsuit.

Mr Neal has said his committee was looking into the effectiveness of IRS mandatory audits of tax returns of all sitting presidents, a way to justify his claim that the panel had a potential legislative purpose.

Democrats are confident in their legal justification and say the president is stalling in an attempt to punt the issue past the 2020 election.