HILLARY CLINTON’S presidential campaign funded research into the now infamous “dirty dossier” on President Donald Trump.

The Associated Press news agency said on Tuesday night that it had received a copy of a letter from an unnamed “person familiar with the matter.”

The letter detailed how Marc Elias, a lawyer for the Democratic National Committee (DNC) and Ms Clinton’s unsuccessful presidential campaign, and his legal firm Perkins Coie acted as a broker for the deal.

In early March 2016 Mr Elias was approached by Fusion GPS, a firm which had already begun probing Mr Trump’s past and alleged links to Russia on behalf of “one or more other clients during the Republican primary contest.”

The leaked letter, sent on Tuesday by Perkins Coie’s general counsel to a lawyer for Fusion GPS, released the research firm from its client confidentiality obligation.

Perkins Coie hired Fusion GPS in April 2016 “to perform a variety of research services during the 2016 election cycle,” the letter said.

Fusion GPS hired former British MI6 spy Christopher Steele to write the reports, first of which were filed in June.

The dossier, published by internet clickbait site Buzzfeed late last year, included lurid accusations against Mr Trump.

The most infamous was that he paid two women to urinate on each other in a hotel bed former president Barack Obama and his wife once slept in.

But the dossier also contained allegations that Russia had meddled in the election by waging a covert smear campaign against Ms Clinton, whose campaign manager’s emails were leaked to WikiLeaks.

It also claimed the Kremlin kept its own blackmail dossier on Mr Trump, potentially compromising his independence.

A DNC spokeswoman said committee chairman Tom Perez was not part of the decision-making and was unaware that Perkins Coie was working with Fusion GPS.

But she insisted: “There is a serious federal investigation into the Trump campaign’s ties to Russia and the American public deserves to know what happened.”

Former Clinton campaign spokesman Brian Fallon tweeted he regretted not knowing about Mr Steele’s hiring — but if he had: “I would have volunteered to go to Europe and try to help him.”