The chairman of the House Intelligence Committee has written to the Director of National Intelligence, James Clapper, asking why this week's reports by the CIA that Russia did hack Democratic campaign documents contradicts what the agency was saying three weeks ago.

Congressman Devin Nunes, a Republican from California, has written to Clapper asking for an urgent briefing on the matter.

Last month Clapper said he lacked 'good insight' about the connection between Russian hacking of Democratic emails and their release by WikiLeaks.

Director of National Intelligence James Clapper (pictured, centre) takes his seat as he arrives at the November 17 hearing before the House Intelligence Committee

In the letter Nunes writes: 'On November 17, 2016 you told the Committee during an open hearing that the intelligence community lacked strong evidence connecting Russian government Cyber-attacks and Wikileaks disclosures.'

But on Friday the Washington Post reported that a secret CIA assessment had concluded that Russia had interfered in the race to boost Trump, although the agency did not have 'specific intelligence' showing Kremlin involvement.

President-elect Donald Trump hit out at the CIA report and said there was no evidence Russia had done anything to help him win the presidency at the expense of Hillary Clinton, who had been promising a tough line with Moscow.

Congressman Devin Nunes (pictured, left) speaks to Paul Ryan (right) during a meeting in Washington. The two Republicans have taken different positions on the Russian hacking

Today Trump announced Rex Tillerson, CEO of ExxonMobil and a friend of Vladimir Putin, as his pick for Secretary of State.

It comes amid speculation that Trump will push for the lifting of sanctions on Russia, which were imposed in 2014 after Putin annexed Crimea after a proxy war with Ukraine.

House of Representatives speaker Paul Ryan has also released a statement saying he supports an investigation the House Intelligence Committee has already started on cyber-threats posed by foreign countries and extremist groups.

The CIA told senators in a secret meeting that they believed hacks on Democratic emails in the election were intended to aid Trump's victory

Donald Trump (left) is expected to appoint Rex Tillerson (right), CEO of Exxon-Mobil as Secretary of State today. Mr Tillerson is known as an ally of Vladimir Putin

Ryan said any Russian intervention was 'especially problematic because under President Putin, Russia has been an aggressor that consistently undermines American interests'.

Underscoring the possible collisions ahead between Trump and the men leading his party in Congress, McConnell and Ryan struck tones markedly more confrontational toward Russia than he has.

When he made his appearance at the House Intelligence Committee, Clapper told Congressman Adam Schiff: 'As far as the WikiLeaks connection, the evidence there is not as strong and we don't have good insight into the sequencing of the releases or when the data may have been provided. We don't have as good insight into that.'

Nunes' letter sent yesterday said: 'According to new press reports, this is no longer the CIA's position.

'I was dismayed that we did not learn earlier from you directly about the reported conflicting assessments and the CIA's reported revision of information previously conveyed to this Committee.'

Nunes writes: 'I am deeply concerned that these press reports may contain unauthorized disclosures of both classified intelligence community (IC) information and the contents of closed intelligence committee proceedings.

'Additionally, if true, reports of conflicting IC assessments call into question the effectiveness of the IC's analytic coordination process regarding this crucial issue.'

Nunes finishes the letter by demanding that Clapper completes, no later than January 13 - a week before Trump's inauguration - an 'analytic and tradecraft review of any IC assessments related to alleged Russian involvement in cyber activities related to the US Presidential election'.

CIA director John Brennan (pictured) may be looking for a new job when Trump takes over, as the President-elect has promised 'changes at the top'

He also demands Clapper provides the committee with 'a written assessment of whether any classified information was disclosed in recent media articles related to Russian involvement in cyber activities related to the US Presidential election.'

The mid-election hacks resulted in leaks of 19,252 emails and 8,034 attachments from the DNC that showed staffers mocking and apparently undermining Bernie Sanders' campaign to be the Democratic candidate.

A second hack saw emails being leaked from the account of Clinton campaign chair John Podesta, including some that apparently discussed payments to the Clinton Foundation in exchange for meetings with Bill Clinton.

The FBI has also been under fire of late because of Director James Comey's decision to publicize the investigation into Hillary Clinton's emails - despite FBI policy which prohibits influencing an election.

Trump told Fox News he believed the Democrats had put out reports about the CIA's remarks, made after a secret assessment of Russia's role in the mid-election cyber attacks on the DNC and Clinton campaign chair John Podesta.

In a secret meeting that emerged Friday through The Washington Post, the CIA told a group of senators that Russian hacks had the specific goal of getting Trump elected.

Previously, the Agency had suggested that the hacks might have been intended to more generally undermine the public's faith in the electoral system, without favoring a particular candidate.

When asked whether he thought that the CIA was trying to overturn the election results, Trump said he didn't think 'they're saying anything'.

The hacks, including one on the emails of Clinton campaign chair John Podesta (pictured) and another on DNC staff, led to much bad publicity for the Democrats during the election

'If you look at the story and you take a look at what they said, there's great confusion. Nobody really knows, and hacking is very interesting,' he said.

'Once they hack if you don't catch them in the act you're not going to catch them.

'They have no idea if it's Russia or China or somebody. It could be somebody sitting in a bed some place. I mean, they have no idea.'

He also said that he believed Democrats were behind the reveal of the CIA's assessment of the hacks.