Breitbart has been denied permanent access to Congress over its top editors' suspected links to a conservative research group and the Donald Trump administration.

The Senate Press Gallery, a group of five journalists who oversee passes for news organisations into the US Senate and House of Representatives, has denied permanent credentials for the ‘alt-right’ website.

An exhaustive New Yorker article, published on the same day, revealed how Trump campaign donor Rebekah Mercer was “highly engaged in Breitbart’s content”.

The committee also wants to know about Breitbart's ties to the Government Accountability Institute (GAI) and is reportedly annoyed at being misled on whether Breitbart office space was banded for commercial lease.

An Independent investigation in December revealed the news website’s London office was not registered for property tax.

“Committee declines to give Breitbart permanent credentials today [and] wants more information,” said Washington Politico media reporter Hadas Gold on Twitter.

“[They’re] now debating how to extend temporary credentials.”

It followed a meeting last month in which Breitbart chief executive Larry Solov was asked by committee members to write a letter outlining the involvement of senior White House adviser and former Breitbart executive chairman Steve Bannon.

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On the night before a second meeting took place, which was postponed from Friday to yesterday, Mr Solov sent a letter stating that Mr Bannon resigned on 13 November and has no “role or interest” in Breitbart News.

But the five journalists, who effectively decide which news organisations can cover the country's most powerful legal chambers, are also concerned about the Mercer family links to Breitbart.

Mr Solov's letter, according to BuzzFeed, admitted that unspecified members of the Mercer family owned Breitbart.

Businessman and computer scientist Robert Mercer was a key financier of Mr Trump’s presidential campaign and has funded the GAI

The links between his daughter Rebekah – who has been nicknamed the “First Lady of the alt-right’ and reportedly lobbied for Jeff Sessions’ as Attorney General – were discussed at length in the New Yorker article on Monday.

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“She reads every story and calls when there are grammatical errors or typos,” one insider was quoted.

Breitbart was reportedly given an extended temporary media pass to Congress until it can provide more information on its links to the GAI, which the Mercer family funds.

The committee lets in organisations which are “editorially independent of any institution, foundation or interest group that lobbies the federal government, or that is not principally a general news organization”.