Senator Ivor Callely has resigned from the Fianna Fáil organisation.
Mr Callely informed the party this evening of his decision to resign his membership with immediate effect.
It follows a meeting today with the Fianna Fáil committee set up to inquire into matters relating to Mr Callely's controversial expenses claims.
In a statement, Mr Callely said the committee had refused an application made on his behalf for a further adjournment of the proceedings of the committee.
He said his resignation arose 'because of the refusal of the committee to particularize alleged conduct 'unbecoming a member' of the Fianna Fáil party.
'Senator Callely considers the committee's findings as constituting a denial of fair procedures to allow him to vindicate his name and refute the allegations made against him.'
Mr Callely said he was 'devastated at the refusal to accord him fair procedures which makes his resignation inevitable'.
He said he will now 'concentrate on clearing his name before the Seanad Select Committee'.
Fianna Fáil said it had accepted Mr Callely's resignation.
In a statement, the party said: 'The committee proceeded in the absence of Senator Callely to conclude its investigation and made a finding of conduct unbecoming a member of Fianna Fáil.'
Mr Callely was suspended without prejudice from the party earlier this month pending the outcome of the inquiry.
