A controversial memo alleging wrongdoing by the FBI in its Russia investigation has been declassified and released to the public – intensifying a battle that has pitched the White House against both the agency and the Justice Department.

The memo, written by Republican House Intelligence Committee Chairman Devin Nunes, raises concerns about the FBI’s securing a Foreign Intelligence Surveillance Act (FISA) warrant as part of the investigation into possible ties between Donald Trump’s presidential campaign and Russia. The memo claims the FBI and Justice Department’s actions in obtaining the warrant against former Trump campaign advisor Carter Page ”represent a troubling breakdown of legal processes established to protect the American people from abuses related to the FISA process”.

President Trump allowed the House Intelligence Committee to release the report to the public on Friday without redactions. The president, who tweeted that morning that the FBI had “politicized the sacred investigative process,” called the contents of the memo “a disgrace”.

While many Republicans in Congress supported the release of the memo, Democrats claimed it represents an attempt to discredit the federal investigation by using “cherry-picked” classified information – one which would set a dangerous precedent that would do “long-term damage” to the US intelligence community.

Both the Justice Department and the FBI objected to the release of the memo, with the FBI releasing a statement on Wednesday detailing "grave concerns" over its accuracy.

Congressional Democrats sent a letter to Mr Trump on Friday warning him against using the memo as a “pretext” to fire either Deputy Attorney General Rod Rosenstein, who is overseeing the investigation, or Special Counsel Robert Mueller who is leading it.

“Firing Rod Rosenstein, [Department of Justice] leadership, or Bob Mueller could result in a constitutional crisis of the kind not seen since the Saturday night massacre,” the Democrats wrote, referring to Richard Nixon’s firing of the Watergate special prosecutor in the 1970s.

Mr Trump declined to say whether he still had faith in faith in Mr Rosenstein when asked on Friday, saying: “You figure that one out.” He added that ”a lot of people should be ashamed” of the allegations made in the memo. Seemingly trying to limit the damage from such remarks, White House officials later briefed that Mr Trump is not considering firing Mr Rosenstein.

The biggest names involved in the Trump-Russia investigation Show all 17 1 /17 The biggest names involved in the Trump-Russia investigation The biggest names involved in the Trump-Russia investigation Paul Manafort Mr Manafort is a Republican strategist and former Trump campaign manager. He resigned from that post over questions about his extensive lobbying overseas, including in Ukraine where he represented pro-Russian interests. Mr Manafort turned himself in at FBI headquarters to special counsel Robert Mueller’s team on Oct 30, 2017, after he was indicted under seal on charges that include conspiracy against the United States, conspiracy to launder money, unregistered agent of a foreign principal, false and misleading US Foreign Agents Registration Act statements, false statements, and seven counts of failure to file reports of foreign bank and financial accounts. Getty The biggest names involved in the Trump-Russia investigation Rick Gates Mr Gates joined the Trump team in spring 2016, and served as a top aide until he left to work at the Republican National Committee after the departure of former Trump campaign manager Paul Manafort. Mr Gates' had previously worked on several presidential campaigns, on international political campaigns in Europe and Africa, and had 15 years of political or financial experience with multinational firms, according to his bio. Mr Gates was indicted alongside Mr Manafort by special counsel Robert Mueller's team on charges that include conspiracy against the United States, conspiracy to launder money, unregistered agent of a foreign principal, false and misleading US Foreign Agents Registration Act statements, false statements, and seven counts of failure to file reports of foreign bank and financial accounts. AP The biggest names involved in the Trump-Russia investigation George Papadopoulos George Papadopoulos was a former foreign policy adviser for the Trump campaign, having joined around March 2016. Mr Papadopoulos plead guilty to federal charges for lying to the FBI as a part of a cooperation agreement with Special Counsel Robert Mueller's investigation. Mr Papadopoulos claimed in an interview with the FBI that he had made contacts with Russian sources before joining the Trump campaign, but he actually began working with them after joining the team. Mr Papadopoulos allegedly took a meeting with a professor in London who reportedly told him that Russians had "dirt" on Hillary Clinton. The professor also allegedly introduced Mr Papadopoulos to a Russian who was said to have close ties to officials at the Russian Ministry of Foreign Affairs. Mr Papadopoulos also allegedly was in contact with a woman whom he incorrectly described in one email to others in the campaign as the "niece" to Russian President Vladimir Putin. Twitter The biggest names involved in the Trump-Russia investigation Donald Trump Jr The President's eldest son met with a Russian lawyer - Natalia Veselnitskaya - on 9 June 2016 at Trump Tower in New York. He said in an initial statement that the meeting was about Russia halting adoptions of its children by US citizens. Then, he said it was regarding the Magnitsky Act, a US law blacklisting Russian human rights abusers. In a final statement, Mr Trump Jr released a chain of emails that revealed he took the meeting in hopes of getting information Ms Veselnitskaya had about Hillary Clinton's alleged financial ties to Russia. He and the President called it standard "opposition research" in the course of campaigning and that no information came from the meeting. The meeting was set up by an intermediary, Rob Goldstone. Jared Kushner and Paul Manafort were also at the same meeting. Getty Images The biggest names involved in the Trump-Russia investigation Jared Kushner Mr Kushner is President Donald Trump's son-in-law and a key adviser to the White House. He met with a Russian banker appointed by Russian President Vladimir Putin in December. Mr Kushner has said he did so in his role as an adviser to Mr Trump while the bank says he did so as a private developer. Mr Kushner has also volunteered to testify in the Senate about his role helping to arrange meetings between Trump advisers and Russian Ambassador to the US Sergey Kislyak. Getty Images The biggest names involved in the Trump-Russia investigation Rob Goldstone Former tabloid journalist and now music publicist Rob Goldstone is a contact of the Trump family through the previously Trump-owned 2013 Miss Universe pageant, which took place in Moscow. In June 2016, he wrote to Donald Trump Jr offering a meeting with a Russian lawyer, Natalya Veselnitskaya, who had information about Hillary Clinton. Mr Goldstone was the intermediary for Russian pop star Emin Agalaraov and his father, real estate magnate Aras, who played a role in putting on the 2013 pageant. In an email chain released by Mr Trump Jr, Mr Goldstone seemed to indicate Russian government's support of Donald Trump's campaign. AP images The biggest names involved in the Trump-Russia investigation Aras and Emin Agalarov Aras Agalarov (R) is a wealthy Moscow-based real estate magnate and son Emin (L) is a pop star. Both played a role in putting on the previously Trump-owned 2013 Miss Universe pageant in Moscow. They allegedly had information about Hillary Clinton and offered that information to the Trump campaign through a lawyer with whom they had worked with, Natalia Veselnitskaya, and music publicist Rob Goldstone. Getty Images The biggest names involved in the Trump-Russia investigation Natalia Veselnitskaya Natalia Veselnitskaya is a Russian lawyer with ties to the Kremlin. She has worked on real estate issues and reportedly counted the FSB as a client in the past. She has ties to a Trump family connection, real estate magnate Aras Agalarov, who had helped set up the Trump-owned 2013 Miss Universe pageant which took place in Moscow. Ms Veselnitskaya met with Donald Trump Jr, Jared Kushner, and Paul Manafort in Trump Tower on 9 June 2016 but denies the allegation that she went there promising information on Hillary Clinton's alleged financial ties to Russia. She contends that the meeting was about the US adoptions of Russian children being stopped by Moscow as a reaction to the Magnitsky Act, a US law blacklisting Russian human rights abusers. Getty Images The biggest names involved in the Trump-Russia investigation Mike Flynn Mr Flynn was named as Trump's national security adviser but was forced to resign from his post for inappropriate communication with Russian Ambassador to the US Sergey Kislyak. He had misrepresented a conversation he had with Mr Kislyak to Vice President Mike Pence, telling him wrongly that he had not discussed sanctions with the Russian. Getty Images The biggest names involved in the Trump-Russia investigation Sergey Kislyak Mr Kislyak, the former longtime Russian ambassador to the US, is at the centre of the web said to connect President Donald Trump's campaign with Russia. Reuters The biggest names involved in the Trump-Russia investigation Roger Stone Mr Stone is a former Trump adviser who worked on the political campaigns of Richard Nixon, George HW Bush, and Ronald Reagan. Mr Stone claimed repeatedly in the final months of the campaign that he had backchannel communications with WikiLeaks founder Julian Assange and that he knew the group was going to dump damaging documents to the campaign of Democratic candidate Hillary Clinton - which did happen. Mr Stone also had contacts with the hacker Guccier 2.0 on Twitter, who claimed to have hacked the DNC and is linked to Russian intelligence services. Getty Images The biggest names involved in the Trump-Russia investigation Jeff Sessions The US attorney general was forced to recuse himself from the Trump-Russia investigation after it was learned that he had lied about meeting with Russian Ambassador to the US Sergey Kislyak. Getty Images The biggest names involved in the Trump-Russia investigation Carter Page Mr Page is a former advisor to the Trump campaign and has a background working as an investment banker at Merrill Lynch. Mr Page met with Russian Ambassador to the US Sergey Kislyak during the 2016 Republican National Convention in Cleveland. Mr Page had invested in oil companies connected to Russia and had admitted that US Russia sanctions had hurt his bottom line. Reuters The biggest names involved in the Trump-Russia investigation Jeffrey "JD" Gorden Mr Gordon met with Russian Ambassador to the US Sergey Kislyak during the 2016 Republian National Convention to discuss how the US and Russia could work together to combat Islamist extremism should then-Republican presidential candidate Donald Trump win the election. The meeting came days before a massive leak of DNC emails that has been connected to Russia. Creative Commons The biggest names involved in the Trump-Russia investigation James Comey Mr Comey was fired from his post as head of the FBI by President Donald Trump. The timing of Mr Comey's firing raised questions around whether or not the FBI's investigation into the Trump campaign may have played a role in the decision. Getty Images The biggest names involved in the Trump-Russia investigation Preet Bharara Mr Bahara refused, alongside 46 other US district attorney's across the country, to resign once President Donald Trump took office after previous assurances from Mr Trump that he would keep his job. Mr Bahara had been heading up several investigations including one into one of President Donald Trump's favorite cable television channels Fox News. Several investigations would lead back to that district, too, including those into Mr Trump's campaign ties to Russia, and Mr Trump's assertion that Trump Tower was wiretapped on orders from his predecessor. Getty Images The biggest names involved in the Trump-Russia investigation Sally Yates Ms Yates, a former Deputy Attorney General, was running the Justice Department while President Donald Trump's pick for attorney general awaited confirmation. Ms Yates was later fired by Mr Trump from her temporary post over her refusal to implement Mr Trump's first travel ban. She had also warned the White House about potential ties former National Security Adviser Michael Flynn to Russia after discovering those ties during the FBI's investigation into the Trump campaign's connections to Russia. Getty Images

Much of the memo concerns the process by which the FBI obtained a FISA warrant to surveil Mr Page, claiming the warrant application was informed largely by a Democrat-funded opposition research dossier compiled by former MI6 agent Christopher Steele.

The memo alleges that then-Deputy FBI Director Andrew McCabe told the Intelligence Committee that the surveillance warrant would not have been sought without this controversial dossier – going further to say that the Mr Steele had already disclosed his anti-Trump bias to the FBI.

Mr Page called the memo an example of “brave and assiduous oversight,” and said he would be updating his pending legal action against the Justice Department.

The memo also briefly mentions texts between an FBI agent and lawyer who worked on the bureau’s investigation into possible Trump campaign ties to Russia. The memo claims the texts demonstrate “clear bias” against Mr Trump and in favour of Hillary Clinton.

However, the memo appears to fall short of the promises made by some Republicans – namely that the evidence it contained would cast doubt on the origins of the Russia investigation. Much of the information it contained involved allegations Mr Nunes and others had previously made public. Democrats also point out that Australian officials told the FBI about another Trump campaign official, George Papadopoulos, had possible knowledge about Russia’s activities. The memo itself states that information about Mr Papadopoulos ”triggered the opening of an FBI counterintelligence investigation in late July 2016.”

In a statement after the release of the memo, Mr Nunes said: “The Committee has discovered serious violations of the public trust, and the American people have a right to know when officials in crucial institutions are abusing their authority for political purposes.” He added that he hoped the memo’s release would “shine a light on the alarming series of events”.

Donald Trump overheard saying he will '100 per cent' release FBI memo

Republicans and Democrats have fiercely debated the release of the memo since last month, when Mr Nunes made it available to members of the House. Adam Schiff, the ranking Democrat on the Intelligence Committee, claimed the memo “mischaracterises highly sensitive classified information” in order to suit Republicans’ political aims.

“Chairman Nunes’ decision ... to publicly release misleading allegations against the Department of Justice and Federal Bureau of Investigation is a shameful effort to discredit these institutions, undermine [special counsel Robert Mueller’s] ongoing investigation, and undercut congressional probes,” Mr Schiff said.

The congressman claimed the FISA warrant to surveil Mr Page had been properly obtained, and was not based entirely on the Steele dossier. He added that Democrats on the House Intelligence Committee would seek a vote to release their own memo, which he claimed pointed out several other factual errors in Mr Nunes’s.

Democratic leaders sent a letter to House Speaker Paul Ryan earlier this week claiming Mr Nunes’s actions were “illegitimate” and “dangerous,” and asking him Mr Ryan to remove the chairman from his role.

But Mr Ryan said on Friday that he supported the release of the memo, claiming it showed a possible violation of civil rights. He said he would also support the release of the Democrats’ response document, once sensitive details had been removed.

The White House later said in a statement that the so-called Nunes memo “raises serious concerns about the integrity of decisions made at the highest levels of the Department of Justice and the FBI to use the Government’s most intrusive surveillance tools against American citizens.”

“This decision was made with input from the President’s national security team — including law enforcement officials and members of the intelligence community, for whom the President has great respect,” the White House added.

It also signalled that Mr Trump would back the release of the Democrat memo, saying the White House was ready to work with Congress to accommodate “oversight requests” on the second memo.

At least one Republican criticised the decision to release the memo, accusing his party of attacking the FBI and Justice Department.

“Our nation’s elected officials, including the president, must stop looking at this investigation through the warped lens of politics and manufacturing partisan sideshows,” Senator John McCain said. ”If we continue to undermine our own rule of law, we are doing [Russian President Valdimir] Putin’s job for him.”

Mr Trump has not signalled what, if any, other steps he will take in response to the memo.