Michael Flynn, former national Security Adviser to US President Donald Trump, has invoked the Fifth Amendment protection against self-incrimination and has declined to comply with a Senate Intelligence Committee subpoena.

“The context in which the Committee has called for General Flynn’s testimonial production of documents makes it clear that he has more than a reasonable apprehension that any testimony he provides could be used against him,” Flynn’s attorneys wrote in a letter they sent to the committee.

Initially, Associated Press news agency cited a source close to the investigation, with the Wall Street Journal, CNN and NPR following with own confirmations.

Flynn's decision comes less than two weeks after the committee issued a subpoena on May 11 for Flynn's documents as part of the panel's investigation into Russia's meddling in the 2016 election.

This request from the senate committee came after Flynn initially refused to provide documents in response to another subpoena dated April 28.

Flynn previously offered to testify before Congress Intelligence Committees, but only in exchange for immunity. Neither committee – House and Senate – accepted the offer from Flynn’s lawyer.

Last week, Senate Intelligence Committee Chairman Richard Burr said that Flynn was "not cooperating" so far with the committee's investigation, but that he hadn’t received a "definitive" answer on whether Flynn would testify.

Flynn and the Russian probe

On February 14, Michael Flynn was forced to resign from his post as National Security Adviser over contacts he had with Russian officials. It then became clear that Flynn had misled Vice President Mike Pence by not disclosing these contacts.

Later it became evident that even Trump had misled his own vice president. Trump kept Pence in the dark and waited nearly three weeks before ousting Flynn.

Then the newly appointed Attorney General Jeff Sessions was forced to recuse himself from the investigation because he failed to disclose two contacts with Russian officials.

In April, it was revealed that Flynn had failed to disclose payments he had received from Russia when applying for government security clearance.

In a series of revelations in May, it was claimed that Trump had asked former FBI Director James Comey to drop the investigation into Michael Flynn.

This information surfaced shortly after Trump had fired Comey. Trump later admitted that the Russia investigation had been a factor in dismissing Comey.

Trump later boasted to Russian Foreign Minister Sergei Lavrov about firing Comey, whom he called "a real nutjob", and claimed that the pressure he felt from the Russia investigation was gone.

The senate committee is one of several congressional inquiries investigating possible collusion between Russia and Trump's 2016 presidential campaign.

Flynn is also the target of other congressional investigations as well as an ongoing FBI counter-intelligence probe and a separate federal investigation in Virginia.

The American Constitution says in its Fifth Amendment that no person "shall be compelled in any criminal case to be a witness against himself".