Former acting U.S. Attorney General Sally Yates was sacked by President Trump in January after she refused to enforce his travel ban.

In the almost three weeks that passed between finding out Flynn misled the Vice President Mike Pence about his contacts with Russia's ambassador to the US and Flynn's resignation, Spicer said, there were no known restrictions to his access to information. Trump has said repeatedly that the leaks of classified information are far more significant than the connections between Russian officials and the Trump campaign.

This development comes after former president Barrack Obama [official website] said he had warned Trump not to hire Flynn [NYT report]. They were issued to associates of Mike Flynn, the former national security advisor to Trump. Mr Obama's concerns about Mr Flynn, which were first reported by NBC News, were largely about his management of the DIA and predated the later concerns about his contacts with the Russian ambassador, Mr Sergey Kislyak.

Yates did not say what Flynn had discussed with ambassador Sergey Kislyak in a number of December 2016 phone calls, which were secretly monitored by USA intelligence. Trump's detractors say it is beyond doubt that Muslims were the ban's intended target, but the administration says it is motivated strictly by national security concerns, an area where USA presidents have wide powers.

Spicer also said that the White House team took the subsequent 11 days to account for "an element of due process, reviewing the situation". "And that includes investigating the nature of any links between individuals associated with the Trump campaign and the Russian government - and whether there was any coordination between the campaign and Russia's efforts".

Trump also addressed remarks from former Director of National Intelligence James Clapper, who testified alongside Yates on Monday.

The White House has a new explanation for its decision not to immediately fire National Security Adviser Michael Flynn after learning that he could be the target of Russian blackmail efforts: The acting attorney general, who supplied that information, was a supporter of Hillary Clinton.

The subcommittee that held Monday's hearing is running one of multiple congressional probes into the Russian Federation interference, along with House and Senate intelligence panels. All the committees are led by Republicans.

The warning was "based on Flynn's role as head of DIA", a former administration official told the AFP. Things that people have said privately about former National Security Adviser Michael Flynn were said in public under oath.

"General Flynn was given the highest security clearance by the Obama administration", he said.