Former German Chancellor Helmut Kohl has defied critics seeking his resignation from parliament because of alleged financial irregularities.

In a speech in Hamburg, Mr Kohl - who is under criminal investigation over illegal party funds - insisted that he had never been corrupt and vowed to stay in parliament to fight for his honour.

"I never pretended to be a saint," he said, but he had "never been open to corruption and everyone who knows me knows that".

But he again refused to name the secret donors who paid out over a million dollars to his Christian Democrats party (CDU).

New revelations

It emerged on Tuesday that an audit of the CDU accounts has uncovered an DM9m ($4.5m) in apparently illicit funds in addition to earlier disclosures.

The party has already admitted to managing secret funds of some DM2m ($1m) for the period from 1993-1998, when Helmut Kohl was chancellor.

The new funds, said Christian Wulff, date back to the period before 1993, when Mr Kohl also was chancellor.

Resignation

Mr Kohl resigned as honorary chairman of the CDU on Tuesday.

A member of the CDU executive, Christa Thoben, has suggested that Mr Kohl follow the example of former CDU Interior Minister Manfred Kanther and resign his seat in the Bundestag.

Mr Kanther had admitted circumventing party financing laws.

Ms Thoben said she hoped Kohl's renunciation of the honorary chairmanship was "not his last word".

CDU leaders have pledged to reveal the names of anonymous donors to clear the party of allegations it accepted cash for political favours, but how they could accomplish that given Mr Kohl's refusal to co-operate remained unclear.

Poll slump

CDU support has fallen by 8% in one week, according to a poll in the weekly Die Woche.

Only 29% now support the CDU, according to a poll taken on Tuesday.

Of those polled, only 30% said CDU party leader Wolfgang Schaeuble was right to stay on in his job, while 57% believed he should have resigned.

Mr Schaeuble offered to resign after his belated admission that he accepted an improper $50,000 cash donation from a wanted arms dealer, but the party executive told him he should stay.

With the CDU facing two important state elections in the next four months, commentators argue that the party's endorsement of Mr Schaeuble signals only a brief stay of execution before the party sought a new leader free of long association with the discredited Kohl.

"The CDU is stumbling deeper into crisis from one day to the next. Virtually all of its leaders are damaged. Confidence is melting like butter in the sun," said the daily Die Welt, a traditional supporter of the party.

Secret donations

So far, disclosures of secret funds have topped DM33m ($17m), including the damaging revelation last Friday by Mr Kanther that the Hesse branch channelled DM13m ($6.8m) in campaign funds through a Swiss account back into Germany when he was state party chairman.

The money was falsely registered as bequests from abroad between 1989-96, some from Jewish donors.

On Tuesday Bonn prosecutors searched the residences of two of his former aides.

Hans Terlinden, a former official at Christian Democratic headquarters in Bonn, and Horst Weyrauch, the party's former tax adviser, are suspected of helping Mr Kohl run his secret accounts, prosecutors said.