The Liberal Democrats have expressed "regret" over the handling of strongly-denied allegations of inappropriate behaviour towards women by a senior party figure.
Chief executive Tim Gordon said it appeared the party "did not fully live up to our political ideals" in dealing with complaints about predecessor Lord Rennard.
The peer - a key party strategist and adviser to a succession of Lib Dem leaders before standing down due to ill health in 2009 - has said he is "deeply shocked" by the allegations, which he "strongly disputes" and regards as a "total distortion" of his character.
Lord Rennard (R) at Lib Dem party conference with Sir Menzies Campbell
Channel 4 News reported on Thursday that two women had claimed Lord Rennard touched them inappropriately.
One of them, Alison Smith, a Lib Dem activist who is now a lecturer at Oxford University, said she had spoken to both the then Lib Dem chief whip Paul Burstow and the party's spokesperson for women and equality, Jo Swinson, about her claims, but claimed no action was taken.
A fresh report by the programme yesterday said more women had come forward with similar stories.
The Lib Dems have launched an internal investigation into the "specific allegations" against Lord Rennard under the party's disciplinary procedures.
Party president Tim Farron is also conducting a review into the way the party dealt with such allegations.
Posting on the Lib Dem Voice website this evening, Gordon said many members would have seen media reports about the allegations and suggestions that the party failed to deal with them adequately.
"It appears that we did not fully live up to our political ideals, and I regret that," he wrote.
"I want to assure you that the Party, and I as Chief Executive, are taking these questions very seriously - both as regards the specific allegations that were made, but also about the Party's procedures for handling complaints of this sort."
He said a five-strong panel of party figures - including at least three women - would be assembled to carry out a "thorough and in-depth" probe into the allegations against Lord Rennard.
At the same time Farron's review will look into how "allegations made in the past have been handled".
"I fully understand the concern from some that, given the nature of the allegations now emerging, an internal review is insufficient," Gordon said.
"We are therefore currently looking at ways to strengthen the independence of this review - we will add non-party members to the group and will seek professional advice from external sources."
The party's whistleblowing representative Kate Parminter will act as a single point of contact for anyone wanting to contribute to the probes.
Gordon continued: "We will not tolerate harassment in this Party. You have my assurance that no one who comes forward will be victimised for raising complaints or coming forward with evidence and we reaffirm not only our commitment to equality provisions but also to taking appropriate disciplinary sanctions against any employee or member who is found, following due process, to have engaged in harassment or impermissible discrimination."
Asked on Channel 4 News yesterday if party leader Clegg had known about the allegations prior to this week, Farron replied: "I do not know, but I am sure that is not the case."
Pressed on whether he believed the Lib Dem organisation had fallen short of its responsibilities, the MP said: "That's what we're going to find out one way or the other."
He added: "I don't want to jump to any conclusions, but I am also determined that we get to the bottom of this. There will be no fear or favour on this."
However, he stressed that every individual was innocent until proven guilty, and there was due process to be gone through.
Swinson said in a statement on Lib Dem Voice: "My focus throughout has been to protect the women who confided in me and, our shared objective, to prevent other women experiencing this kind of behaviour.
"All the time I was careful to respect their wish for privacy and, for that matter, their right not to be harassed by the press.
"I took action and ensured that others took action. I told the women who had confided in me what I had done to try to put a stop to any inappropriate behaviour, and encouraged them to let me know if they became aware of any further incidents.
"I welcome the review into how the party responded to this situation so that lessons can be learned. It is important that a proper process is followed and I look forward to the opportunity to contribute to the review."
Responding to the initial Channel 4 News allegations, a spokesman for Lord Rennard said: "He regards the report as a total distortion of his character.
"Not a single complaint of misconduct was made against him to his knowledge during the 27 years he worked for the Liberal Democrat party. Despite the claim made by one woman in the report, Lord Rennard continued working closely with her for ten years after the alleged event described.
"Until this matter is resolved he will withdraw from the Federal Policy Committee on which he serves and temporarily stand aside from the Liberal Democrat group in the House of Lords to seek to avoid any embarrassment to the party.
"He will remain a member of the Liberal Democrats and will continue to devote himself to good causes through his work in the House of Lords and elsewhere."
After the follow-up report last night Lord Rennard said in a statement: "I absolutely deny any suggestion of improper touching, nor did I invite a woman to join me in my room.
"I note that these alleged instances supposedly took place in public bars with other people present.
"I am disappointed and angry that anonymous accusations from several years ago are once again being made public in this manner in a clear attempt to damage my reputation.
"Let me reiterate that in 27 years working for the Liberal Democrat party, not a single personal complaint was ever made against me to my knowledge."