Michael Flynn said to refuse Senate subpoena on Russia investigation

Former US national security adviser Michael Flynn is reportedly set to decline a subpoena from the Senate demanding information on an investigation into his alleged links with Russia during last year's presidential election.

Flynn is at the centre of the investigation into President Donald Trump's election campaign and its purported links with the Kremlin, after he resigned a matter of weeks after his appointment to the key administration position.

According to a report from The Associated Press, Flynn will plead the fifth amendment of the US constitution after the Senate intelligence committee issued the subpoena for documents.

The former general asked for immunity in exchange for testimony in March, but the Senate committee is yet to take him up on that offer.

Trump's administration has come under fierce pressure in recent weeks as further revelations about alleged links with the Kremlin come out, which allegedly led to the President asking sacked FBI director James Comey to drop the investigation into Flynn.

AP cited a person with direct knowledge of the matter in the report, adding that Flynn will make use of the constitutional amendment, which allows protection against self-incrimination.