Donations to the Clinton Foundation plummeted amid Hillary Clinton's failed presidential run, it has been revealed.

The non-profit organization's latest tax filings show contributions fell 37 per cent to $108million – down from $172million in 2014, according to the New York Post.

Donations fell as the former Secretary of State left the group in April last year shortly after announcing her run for the White House.

Her departure also meant that revenue brought in from paid speeches plunged from $3.6million in 2014 to just $357,500.

The foundation became an issue during the presidential campaign when Donald Trump pledged to appoint a special prosecutor to investigate it amid pay-to-play allegations.

Trump called the foundation 'the most corrupt enterprise in political history' adding, 'It must be shut down immediately.'

It's not known whether Trump will keep his promise as he has since backed down in a recent interview on his vow to investigate Clinton again for her use of a private email server, calling the Clintons 'good people.'

But Rep. Jason Chaffetz, head of the House Oversight Committee, has suggested that the investigation into the foundation will continue.

Last year, Charity Navigator placed the foundation on its watchlist, a feature it added in 2014.

In the Clinton Foundation's case, the watchdog cited multiple concerns, including news reports about the foundation accepting donations from foreign governments.

It had voluntarily sworn off that practice while Clinton led the State Department, but the donations started again when she left her post.