VATICAN CITY - AN APOLOGY from Holocaust-denying bishop Richard Williamson failed to placate the Vatican on Friday which called on him to 'unequivocally and publicly' withdraw his comments.

Vatican spokesman Federico Lombardi said a letter of apology from Williamson 'doesn't seem to have respected the conditions' set by the Vatican on February 4, under which the bishop was to 'distance himself absolutely and publicly' from his positions concerning the Holocaust.

In a letter to the Vatican released on Thursday, Williamson apologised to those he offended with his remarks but stopped short of withdrawing them.

Outraged religious groups said Williamson had not retracted claims that no Jews perished in the gas chambers.

Leading German religious groups, including the influential Catholic Church, sharply rejected the apology and a prominent Jewish organisation accused him of continuing to hold his controversial views.

'By clearly refusing to retract his malicious lies, Williamson has again made clear that he is convinced anti-Semite and diehard Holocaust-denier, who calls into question the genocide of six million Jewish people,' said Charlotte Knobloch, the president of Germany's Central Council of Jews.

German Justice Minister Brigitte Zypries meanwhile refused to rule out possible legal action. 'Germany could act within the framework of a European arrest warrant,' she said.

Williamson said in the letter: 'Observing these consequences I can truthfully say that I regret having made such remarks.'

'If I had known beforehand the full harm and hurt to which they would give rise, especially to the Church, but also to survivors and relatives of victims of injustice under the Third Reich, I would not have made them,' he said.

The bishop has been at the centre of a raging controversy after saying in comments broadcast by Swedish television last month: 'There was not one Jew killed by the gas chambers. It was all lies, lies, lies.' -- AFP