Donald Trump has backed calls for the mysterious memo to be made public in order to increase “transparency”, it is reported.

White House official Marc Short said: “We don’t know what’s in the memo. It's classified, I haven't seen it.

“But I think the President generally is on the side of transparency. And so, yes, I think he believes that that should be put out.”

Releasing the document would be “extraordinarily reckless” the FBI has warned as it fights to keep it secret.

The memo was written by staff from the office of Republican Devin Nunes – who is the chairman of the House Intelligence Committee – after they were granted access to classified documents.

It is thought the four-page document contains the allegation that the FBI abused surveillance powers to spy on President Trump’s campaign during his successful 2016 election campaign.

The FBI is currently conducting an investigation into collusion between the Trump campaign and Russian agents who are thought to have tried to influence the election result.

To justify the surveillance the US security service reportedly sighted the Steele Dossier which includes the notorious allegations that Trump was filmed in a Russia hotel room.

Trump campaign advisor Carter Page was the target of the surveillance warrant obtained in 2016.

Now a group of Republicans are calling for the secret report to be made public alleging it shows bias against Trump and his administration.

They claim the document shows Robert Mueller’s investigation into Russian interference is motivated by political bias within the FBI.

The bureau is fighting calls to go public claiming it would reveal secret sources and could ruin a current investigation.

The Department of Justice has said that releasing the document would not comply with the terms struck with Republican Speaker Paul Ryan’s office when the agreement was made to hand over the information to form the Nunes memo.

Republican lawmaker Trey Gowdy said: “I want the bureau to know everything that’s in the memo. I think you’ll be surprised.

‘It is not a hit piece on the department and the FBI. I would not have participated in it if that’s what it was.”

Democrats revealed they wrote their own memo to expose the misleading character of the Republicans’ document.

High-ranking Republican Lindsey Graham expressed reservations about making the original memo public in response.

He called for the document to be seen by an outside group with no political bias.