Rep. John Conyers speaks during a hearing of the House Judiciary subcommittee on Capitol Hill in Washington on April 4. (Alex Brandon/AP)

House Minority Leader Nancy Pelosi (D-Calif.) called for a formal ethics investigation into Rep. John Conyers (D-Mich.) following allegations he sexually harassed female staff and reached a settlement with an aide who claimed she was fired for rejecting his advances.

"As Members of Congress, we each have a responsibility to uphold the integrity of the House of Representatives and to ensure a climate of dignity and respect, with zero tolerance for harassment, discrimination, bullying or abuse," Pelosi said in a statement Tuesday.

"As I have said before, any credible allegation of sexual harassment must be investigated by the Ethics Committee," she said.

Pelosi is the most senior lawmaker yet to call for an ethics probe into Conyers's behavior. She did not address whether Conyers, the ranking member of the powerful House Judiciary Committee, should step down from that position.

Conyers confirmed the existence of a settlement Tuesday but stressed he did not admit fault in the case, first reported late Monday by BuzzFeed.

"I expressly and vehemently denied the allegations made against me, and continue to do so," Conyers stated Tuesday.

"My office resolved the allegations — with an express denial of liability — to save all involved from the rigors of protracted litigation. That should not be lost in the narrative," he stated.

A growing chorus of Democrats has called for an ethics investigation into the matter.

"The allegations against Ranking Member Conyers are extremely serious and deeply troubling," said Rep. Jerrold Nadler (N.Y.), Judiciary's second most senior Democrat, in a statement.

"Obviously, these allegations must be investigated promptly by the Ethics Committee. There can be no tolerance for behavior that subjects women to the kind of conduct alleged," Nadler stated.

Rep. Jackie Speier (D-Calif.), a leading voice on the problem of sexual harassment on Capitol Hill, drew attention to evidence that Conyers handled the settlement by placing his accuser back on his payroll.

"Beyond the sexual harassment allegations are allegations that call into question the amount of money that is used to settle sexual harassment cases, and whether some Members are using their tax payer-funded office budgets to make settlements under the guise of severance payments," Speier said in a statement, also calling for an ethics investigation.

Citing documents from the case, BuzzFeed News reported late Monday that Conyers settled a wrongful dismissal complaint in 2015 with an unidentified woman who alleged that he "repeatedly made sexual advances to female staff that included requests for sex acts." The report included other allegations of harassment by Conyers.

Speaker Paul D. Ryan (R-Wis.) called the report "extremely troubling" in a statement. He noted a recent rules change requiring members and staff to undergo anti-harassment training and said the House Administration Committee is reviewing congressional workplace policies.

"Additional reforms to the system are under consideration as the committee continues its review," Ryan stated Tuesday. "People who work in the House deserve and are entitled to a workplace without harassment or discrimination."

Pelosi denied knowledge of the alleged settlement in a statement first shared with BuzzFeed, citing the requirement that the parties keep their agreement confidential.

The Washington Post is examining workplace violations on Capitol Hill and the process for reporting them. To contact a reporter, please email kimberly.kindy@washpost.com, michelle.lee@washpost.com or elise.viebeck@washpost.com.