WASHINGTON –

U.S. 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 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 U.S. election and whether the Trump campaign colluded with Moscow.

The Republican president, who formally launched his re-election bid last week, repeatedly railed against Mueller's probe during the two-year investigation and accused several of the team's investigators of being Democrats targeting him.

He has also accused Mueller of having a business conflict of interest tied to Trump's Mar-a-Lago resort in Florida, as well as for meeting with him early in Trump's White House term about the possibility of leading the FBI a second time.

Mueller, who was subpoenaed, will testify about his report in front of the Democratic-led House of Representatives Judiciary and House Intelligence Committees on July 17.

In his report released in April, Mueller found that Russia did meddle in the 2016 U.S. election but that the Trump campaign did not illegally conspire with Russia to influence the vote. He also laid out a number of instances where Trump had committed obstruction of justice but stopped short of concluding the president had committed a crime.

Mueller, also a Republican, previously served as the director of the FBI.