Image copyright Reuters Image caption The 10-page memo was redacted to avoid revealing intelligence gathering sources

Congressional Democrats have released a memo that counters Republican claims of bias in the investigation into alleged Russian meddling in the 2016 election.

The memo says the FBI and US justice department did not - as the Republicans allege - abuse powers to spy on former Trump campaign aide Carter Page.

Mr Page was investigated over concerns that he was a Russian agent.

The memo was issued by Democrats on the House Intelligence Committee. Mr Trump called it a "political and legal bust".

The president has repeatedly denied any collusion between his campaign and Russia.

The 10-page Democratic memo was released on Saturday. Parts of the document were redacted to avoid revealing intelligence gathering sources.

It calls a Republican memo published by Republican members of the Intelligence Committee earlier this month a "transparent effort to undermine" the FBI, the justice department and investigations into possible collusion between the Trump campaign and Russia.

Image copyright Reuters Image caption Carter Page is a former Trump campaign aide

What are the main arguments?

One: The Steele dossier: The Republican document alleged that the FBI used unsubstantiated evidence to spy on Carter Page, who was put under electronic surveillance by the intelligence agency.

Central to that claim was the charge that, in its application to a court for a surveillance warrant against Mr Page in 2016, the FBI had relied upon evidence contained in a dossier compiled by former British spy Christopher Steele - without revealing that his findings had been funded in part by the Hillary Clinton campaign.

The Democrats argue in their document that officials had not relied on Mr Steele's dossier alone but had provided "additional information from multiple independent sources that corroborated Steele's reporting", informing the court of existing FBI operations against the Russians over their alleged campaign to influence the US election.

Furthermore, they reveal that the FBI had interviewed Mr Page over his Russian links and opened its inquiry months before the Steele dossier had been received.

Two: Who paid Steele? Democrats also reject the allegation that failure to mention explicitly that the dossier had been funded by the Clinton campaign constituted bias. In their rebuttal, Democrats argue that the Steele dossier had been commissioned by someone who wanted to discredit Mr Trump.

Three: Yahoo News - a source? The Democratic memo also challenges the Republican point that the FBI had used a Yahoo article to corroborate Mr Steele's claims. The memo says the aim was to inform the court of Mr Page's "public denial of his suspected meetings in Moscow".

Four: Judges were Republican In order to demonstrate the lack of political bias, the Democratic memo also points out that judges on the court that agreed to a surveillance warrant for Carter Page had all been appointed by Republicans.

Five: It proved useful And the latest memo adds that the investigation into Mr Page's activities had yielded "valuable intelligence".

Does the release of the memo end this argument?

Unlikely.

Adam Schiff, the top Democrat on the intelligence committee, said the document should "put to rest" Republican assertions of wrongdoing.

But the Republicans issued a new document to reject the Democratic memo point by point.

What has the inquiry found so far?

Robert Mueller, the special counsel conducting the inquiry into alleged Russian interference, has charged 19 people, including four former Trump advisers.

Mr Trump's former campaign chairman Paul Manafort and business associate Rick Gates have been charged with tax and bank fraud and conspiracy to launder money.

Michael Flynn, a former US national security adviser, pleaded guilty to lying to the FBI over meetings he had with the Russian Ambassador, Sergei Kislyak.

George Papadopoulos, a former Trump campaign adviser, admitted lying to the FBI about his contacts with Russians.

The list also includes 13 Russians charged with tampering in the 2016 US election.

But, as President Trump has repeatedly pointed out, the ongoing inquiry has yet to file a charge that any of his associates colluded with an alleged Kremlin plot to influence the result of the 2016 presidential election.