WASHINGTON (Reuters) - Roger Stone, a longtime ally of President Donald Trump, said on Thursday he had agreed to testify in a closed hearing to the House of Representatives Intelligence Committee in its investigation of possible Russia meddling in the 2016 presidential election.

FILE PHOTO: Political advisor Roger Stone poses for a portrait following an interview in New York City, U.S., February 28, 2017. REUTERS/Brendan McDermid

“All 20 members of the committee will be present for the hearing,” Stone, an informal adviser to the Republican president, said in a statement.

The hearing will be held on Sept. 26.

Stone said he had asked for an open, public hearing in the interest of full transparency. Since it will be closed, he has requested an immediate release of transcripts to avoid confusion about his testimony.

“I very much look forward to testifying and I am anxious to correct a number of the misstatements by committee members regarding my activities in 2016,” Stone said.

A spokeswoman for Representative Mike Conaway, the Republican in charge of the committee investigation, declined comment.

The House panel is one of the main congressional committees investigating allegations that Russia sought to interfere in the 2016 U.S. election and probing whether any Trump associates colluded with Moscow.

Russia denies any such efforts, and Trump has dismissed any talk of collusion.

Media reports earlier this year said that Stone was among Trump associates whose communications and financial transactions were being examined by the Federal Bureau of Investigation and others as part of the broad investigation.

At the time, Stone denied contacts or collusion with the Russians.