Donald Trump knew for weeks that Michael Flynn withheld the truth on his call with Russia

The White House has admitted Donald Trump was told several weeks ago that national security adviser had not told the truth about a telephone call with a Russian diplomat - and chose not to fire him immediately.

Michael Flynn handed in his resignation amid mounting controversy over his interaction with Russian officials, and a false assurance he gave that he had not discussed the issue of sanctions. Senior officials in Mr Trump’s team were told a month ago by the acting US attorney general they feared the falsehoods made him vulnerable to potential blackmail from Moscow.

Vice President Mike Pence was also reportedly told about Mr Flynn's interactions with Russia, 11 days after Mr Trump found out.

On Tuesday, White House spokesman, Sean Spicer, said Mr Flynn was not ousted from his post because of legal issues, but because the trust between him and Mr Trump had eroded.

“We had been reviewing this for weeks. It got to trust issues,” Mr Spicer told reporters. “It got to the point where Mr Flynn had to leave.”

The White House has been bombarded with questions about what Mr Trump knew about Mr Flynn’s interactions with Russia. Indeed, senior Democrats have called for an independent investigation into possible links between not just Mr Flynn and Russia, but other senior members of the Trump team.

Mr Flynn, 58, had found himself at the centre of a gathering storm after it emerged he had spoken with a Russian diplomat about the issue of US sanctions before Mr Trump took office, and indicated the relationship between the two countries would improve under a new administration.

Sanctions had been imposed by Barack Obama in response to Russia’s alleged cyber-interference in the presidential election.

Mr Flynn had originally denied discussing sanctions, and senior officials including Mike Pence. But when it emerged that US intelligence officials had been monitoring the call to the Russian Ambassador to Washington, Mr Flynn had to reverse course.

On Monday evening, the Washington Post reported that a month ago, the acting attorney general Sally Yates - an official whom Mr Trump subsequently fired - had informed the White House that she believed Mr

Flynn had misled senior administration officials about the nature of his communications with the Russian ambassador. She warned that as a result of that, the national security advisor was potentially vulnerable to Russian blackmail. Within hours, Mr Flynn had resigned.

Mr Spicer said the Department of Justice had spoken to Mr Trump about this on January 26. He said that Mr Trump spoken with White House legal counsel, Donald McGahn.

He said Mr Trump did not believe that Mr Flynn had breached the law. However, he said that Mr Trump had concluded he could not trust the man tasked with advising him on matters of national security.

“It was not a legal issue, it was a trust issue,” he said. “General Flynn is a dedicated public servant, he has served this country admirably. I think the president has appreciated his service to the country.”

He added: “It was not a matter of law. It was a matter of trust.”

The revelations were another destabilising blow to an administration that has already suffered a major legal defeat on immigration, botched the implementation of a signature policy and stumbled through a string of embarrassing public relations missteps.

Republican Senator Lindsey Graham, a longtime Russia critic, said Congress needed to know what Mr Flynn discussed with the ambassador and why.

“The idea that he did this on his own without any direction is a good question to ask,” Mr Graham said, according to the Associated Press.

House Speaker Paul Ryan said Trump made the right decision in asking Mr Flynn to step down.

“You cannot have the national security adviser misleading the vice president and others,” Mr Ryan said.

Mr Trump, who has been conspicuously quiet about Mr Flynn’s standing for several days, said on twitter that the real “story here is why are there so many illegal leaks coming out of Washington?”