Aides: Trump Jr. to Testify Privately Before US Senate Panel Thursday

FILE - Donald Trump Jr. is interviewed by host Sean Hannity on a Fox News Channel television program, July 11, 2017.

President Donald Trump's oldest son, Donald Trump Jr., on Thursday will testify privately to the Senate Judiciary Committee, which is looking into allegations of Russian interference in the 2016 U.S. election, Senate aides said on Wednesday.

Trump Jr. had been invited to testify in public in a hearing in July, but reached an agreement to speak privately with committee staff.

"We look forward to a professional and productive meeting and appreciate the opportunity to assist the committee," Alan Futerfas, a lawyer for Trump Jr., said in a statement.

Russia has loomed large over the first six months of the Trump presidency. U.S. intelligence agencies have concluded that Russia worked to tilt last year's presidential election in favor of Trump, the Republican candidate.

Special counsel Robert Mueller is leading an investigation, which is also examining potential collusion with Russia by the Trump campaign. Several congressional committees are also looking into the matter.

Separately, Susan Rice, who was national security adviser for former President Barack Obama, testified on Tuesday before the House Intelligence Committee for about four hours.

FILE - Susan Rice, U.S. National Security Adviser in the administration of Barack Obama, July 21, 2017.

Erin Pelton, a spokeswoman for Rice, said she had met voluntarily with the committee as part of its investigation.

"Ambassador Rice remains fully supportive of bipartisan efforts to determine the extent and scope of Russia's outrageous efforts to interfere in the 2016 election," she said in a statement.

Rice had been subpoenaed by the committee as it looked into Republican concerns about whether anyone from the administration of Obama, a Democrat, had asked to "unmask" names of Trump campaign advisers inadvertently picked up in top-secret foreign communications intercepts.

Several U.S. officials have told Reuters that all such requests by Obama administration officials were properly scrutinized and appropriate.

Moscow has denied any meddling. Trump denies any collusion by his campaign, while regularly denouncing the investigations as political witch hunts.