WASHINGTON (Reuters) - A congressional panel on Wednesday dropped attempts to force the founder of a firm that hired a former British spy to compile a dossier of links between the 2016 Trump election campaign and Russia to testify under oath, a lawyer for the firm said.

Rep. Adam Schiff (D-CA) and Rep. Mike Conaway (R-TX) talk, as executives appear before the House Intelligence Committee to answer questions related to Russian use of social media to influence U.S. elections, on Capitol Hill in Washington, U.S., November 1, 2017. REUTERS/Aaron P. Bernstein

Fusion GPS lawyer Joshua Levy said in a statement that Republican Representative Mike Conaway and Democrat Adam Schiff, leaders of the U.S. House Intelligence Committee’s investigation of Trump campaign contacts with Russia, had “agreed to withdraw a subpoena” served on Glenn Simpson, a founder of the firm.

“Mr. Simpson will instead sit for a voluntary interview next week, and nothing will be said at that interview – per the agreement of Mr. Conaway and Mr. Schiff – shall interfere with Mr. Simpson’s ability to assert privileges in this investigation,” Levy said.

Simpson and Levy met with the committee for about three hours on Wednesday, reaching the agreement for Simpson to testify to the panel behind closed doors on Nov. 14, Schiff and Conaway told reporters.

Levy said that under the agreement, Fusion GPS would be allowed to “cooperate while honoring its obligations to clients.”

Three congressional committees and a special counsel are looking into former MI6 officer Christopher Steele’s reports that are central to investigations into U.S. allegations that Russia tried to help Donald Trump’s campaign. Russia has repeatedly denied the allegations and President Trump has called the probes a witch hunt.

Fusion lawyer Levy said that on Aug. 22, Simpson had appeared before the Senate Judiciary Committee and answered questions for 10 hours. Two other Fusion investigators also were summoned before the House Intelligence Committee, but they declined to respond to questions, citing their rights under the First and Fifth Amendments to the U.S. Constitution, which protect free speech and allow legal witnesses to avoid self-incrimination.

The committee chairman, Republican Devin Nunes, recused himself from the investigation, but he and some other Republicans have continued seeking information about who paid Fusion for the dossier. The company has resisted such disclosures, saying it promises its clients confidentiality.

A conservative website, the Washington Free Beacon, has already said that it hired Fusion to research Trump and other Republican candidates. A law firm representing the Democratic National Committee and Hillary Clinton’s campaign later paid Fusion $1.02 million for work on Trump and Russia.

A lawsuit by Fusion against its own bank seeking to block a subpoena the House Intelligence Committee issued for two years of the bank’s records is still pending in U.S. District Court in Washington, D.C., a Fusion representative said.