US President Joe Biden “never had any involvement” in the business dealings of other members of his family, his brother James Biden has said during a voluntary private interview on Capitol Hill as part of House Republicans’ impeachment inquiry.

“I have had a 50-year career in a variety of business ventures. Joe Biden has never had any involvement or any direct or indirect financial interest in those activities,” James Biden said in an opening statement to members of Congress obtained by The Associated Press.

The interview with James Biden is the latest in a series that Republicans have conducted as they seek to rebuild momentum for an impeachment process surrounding the Biden family’s overseas finances that has stalled in recent months.

Criticism over the lack of evidence directly related to the president has grown even among those in the Republican Party who have thrown cold water on allegations that Joe Biden was directly involved in his family members’ supposed efforts to leverage the last name into corporate paydays domestically and abroad.

The Republican investigation was undercut again last week when an FBI informant who claimed there was a multimillion-dollar bribery scheme involving the president, his son Hunter, and a Ukrainian energy company was charged with fabricating the story.

The informant’s claims had been central to the Republican effort in Congress to investigate the president and his family. A lawyer for Hunter Biden, who is expected to give a deposition next week, said the charges show the probe is “based on dishonest, uncredible allegations and witnesses”.

Both James and Hunter Biden were subpoenaed by the committee in November. Lawyers for James Biden have said that there was no justification for the subpoena because the committee had already reviewed private bank records and transactions between the two brothers. The committee found records of two loans that were made when Joe Biden was not in office or a candidate for president.

“With my appearance here today, the committees will have the information to conclude that the negative and destructive assumptions about me and my relationship with my brother Joe are wrong,” James Biden said in his. “There is no basis for this inquiry to continue.”

But Republicans have pushed back on the Biden family’s defence, saying the evidence they have gathered since early last year paints a troubling picture of “influence peddling” in the family’s business dealings, particularly with international clients.