Washington: US President Donald Trump, without offering evidence, on Wednesday directly accused former Special Counsel Robert Mueller of committing a crime, saying Mueller had illegally "terminated" FBI communications as part of his Russia investigation.

The Justice Department declined to comment.

"Mueller terminated them illegally. He terminated all of the emails. ... Robert Mueller terminated their text messages together. He terminated them. They're gone. And that's illegal. That's a crime," Trump said in an interview with Fox Business Network, referring to two former Federal Bureau of Investigation employees who exchanged disparaging messages about the president.

Trump made the remarks ahead of Mueller's scheduled testimony before lawmakers next month about his investigation into Russian interference in the 2016 US election and whether the Trump campaign colluded with Moscow.