Donald Trump returned to an old suspect he has accused in the election meddling scandal - the "400 pound genius sitting in bed and playing with his computer".

Days after FBI special counsel Robert Mueller brought charges against 13 Russians for trying to skew the 2016 American presidential election vote, Trump revived his alternative suspect.

Trump tweeted in Sunday (18 February): "I never said Russia did not meddle in the election, I said 'it may be Russia, or China or another country or group, or it may be a 400 pound genius sitting in bed and playing with his computer.'

"The Russian 'hoax' was that the Trump campaign colluded with Russia - it never did!"

But his tweet forgot that his previous communications looked for other potential suspect to disparage the investigation, not help it.

The charges brought by special counsel Robert Mueller on Friday (16 February) are a major development in his ongoing probe into last year's election between Republican winner Trump and Democratic nominee Hillary Clinton.

The FBI and several congressional committees are looking into whether Russia attempted to influence the US election.

But the White House has said the indictment from Mueller shows that the Trump campaign did "nothing wrong".

In a another tweet on Sunday Trump blamed the FBI for not picking up on a January tip off that that 19-year-old Nikolas Cruz, who killed 17 people at a Florida high school this week, was planning an attack.

Trump wrote: "Very sad that the FBI missed all of the many signals sent out by the Florida school shooter. This is not acceptable.

"They are spending too much time trying to prove Russian collusion with the Trump campaign - there is no collusion. Get back to the basics and make us all proud!"

At the weekend Russia's foreign minister, Sergei Lavrov, dismissed the charges levelled by the FBI special counsel against 13 Russians as "blather" until he had seen the facts.

But Trump's own National Security Adviser, H R McMaster, said evidence of Russian meddling was "now incontrovertible".

The 37-page indictment by the FBI special counsel accuses 13 Russians and three firms of conspiracy to defraud the United States, conspiracy to commit wire fraud and aggravated identity theft.

Among a range of activities, the document alleges that the group operated with a monthly budget of as much as $1.25m, organised and promoted political rallies within the US and promoted information that disparaged Hillary Clinton.