President Donald Trump launched yet another blistering attack on the integrity of the FBI on Sunday, saying the agency's reputation was in "tatters".

In a series of remarks on Twitter, Mr Trump also took aim at former director James Comey and reiterated his denial that he asked the sacked FBI chief to drop the investigation into General Michael Flynn, his former national security adviser.

He wrote: "After years of Comey, with the phony and dishonest Clinton investigation (and more), running the FBI, its reputation is in Tatters - worst in History! But fear not, we will bring it back to greatness!"

Earlier he wrote: "I never asked Comey to stop investigating Flynn. Just more Fake News covering another Comey lie."

The salvo came amid a flurry of developments in Special Counsel Robert Mueller's inquiry into alleged Russian interference in the US election this week.