Mr Clarke was identified in the release - sent to US commentators in advance of Tony Blair's visit to Washington earlier this month - as a member of the "secretive grouping called The Supper Club" . The Tory document said the club was opposed to Allied intervention in the Gulf War.
Mr Clarke, who Labour said had already secured damages, full costs and an apology from the Mail on Sunday for making the same allegation in March 1991, said he had been "deeply hurt and angered" by the allegations and his solicitors Lewis Silkin are also considering possible libel action in the US where the allegations have also been published.
The Opposition front-bench spokesman added: "This is yet another example of the gross incompetence of Brian Mawhinney and Central Office. In their haste they have failed to check their facts and in the process repeated the libel."
Stephen Groom, a partner in Mr Clarke's solicitors Lewis silkin, said yesterday: "These allegations are highly damaging to our client both personally and professionally and their repetition has caused him considerable distress and embarrassment."
The two page document also names John Prescott, Margaret Beckett, Michael Meacher, Mr Clarke and Clare Short as members of "The Supper Club".
Conservative Central Office said yesterday that Dr Mawhinney had not yet received the communication from Mr Clarke's solicitors and could not comment in advance of doing so.