Former Finance Minister Giorgos Papaconstantinou has been ousted from PASOK after he was linked by reports with the tampering of the so-called Lagarde List.
The center-left party issued a statement on Friday a few hours after judicial sources indicated that the latest version of the list of Greeks with deposits in the Geneva branch of HSBC had three names that were not on the list being investigated by prosecutors.
These three names were identified as relatives of Papaconstantinou's.
"It is regrettable that according to the prosecutors' investigation there are clear indications that the list has been tampered with... there is, therefore, a major issue regarding the responsibility of Giorgos Papaconstantinou since he is the one who handled the issue in the worst possible way and after two years declared he had lost the original CD,» said PASOK in its statement.
"It is clear that Mr Papaconstantinou no longer belongs to PASOK."
However, the Socialists also sought to defend the record of its leader, Evangelos Venizelos, who succeeded Papaconstantinou as finance minister.
Venizelos had been roundly criticized after producing a copy of the list from his personal records when authorities admitted in October that they could not trace the original.
"Following the latest developments, it is clear that the attempt to target and defame Evangelos Venizelos has failed and that its instigators, mainly SYRIZA, owe PASOK and its president an apology,» said the party's statement.
PASOK also called for an investigation into how the details of the list were obtained by journalist Costas Vaxevanis and published in his weekly Hot Doc magazine. The Socialists suggested this was part of an organized attempt to discredit Venizelos.
"National interest demands the truth about everything and everyone,» PASOK said. «There is no room for party political tricks, games of conspiracy and intentional confusion regarding the positions adopted by certain people."