Letters to political donors leaked to the Opposition by Labor sources show Mr Tripodi used his letterhead as Fairfield MP to thank at least three donors for their payments in March 2004.

He also held campaign committee meetings in his electorate office on several dates in 1999 and 2004 according to leaked minutes and invitations provided to the Herald.

At least one of these meetings involved Chris Bowen, now the federal Assistant Treasurer.

In the 2004 council elections, the present member for Lakemba, Nick Lalich, and the present member for Smithfield, Ninos Khoshaba, were council candidates.

When the Herald asked Mr Khoshaba about whether Mr Tripodi used his office for council campaigns, he said: "You'd have to ask Joe about that. I don't want to make any comment."

The rules of the Parliamentary Remuneration Tribunal state that the "electorate office provided for a member of the Legislative Assembly is not to be used as an election campaign office. Additional entitlements should not be used to fund … costs previously borne by political parties which are not principally related to a member's parliamentary or electorate duties".

Last night the office of the Opposition Leader, Barry O'Farrell, referred the matter to the Speaker, Richard Torbay. Penalties for such breaches can include expulsion from Parliament.

Mr Tripodi was forced to admit yesterday that he had wrongly used the letterhead, claiming it was an "oversight" on his part and that his records showed it occurred with only one letter. He denied his office was used as a campaign office but admitted campaign meetings were held there.

One letter to a Faiz Said, dated March 3, 2004 on Mr Tripodi's letterhead, says: "I would like to extend my appreciation for your political donation of $750.

"Your generous support to the Fairfield Municipal Committee is greatly appreciated."

Speaking from Tokyo, where he is on a 20-day trip in a bid to sell electricity retailers, Mr Tripodi said: "Some meetings were held in my office where election matters were discussed along with other local issues. But the council campaign was not run out of my electorate office.

"My records show one donor acknowledgement letter was sent on my MP letterhead. This was an error. My records show other acknowledgement letters were sent on ALP letterhead.

"Apart from the oversight with the letterhead, I have checked records and the logistic support allowance forms and they show that public funds were not used for the 2004 council election campaign."

When told the Herald had other letters on his letterhead, Mr Tripodi said: "I only have a record of one acknowledgement letter being sent on my MP's letterhead, but I accept there may have been more."

Asked where the Labor councillors' campaign office was, if not at his electorate office, the minister said: "There was no campaign office. The distribution of material was co-ordinated from a number of locations, including the homes of branch members."

Mr O'Farrell said: "This is a clear breach of the guidelines and the Speaker needs to act. There should be an investigation to establish how broad the issues were. The Speaker can require funds to be repaid … [and] can refer the matter to ICAC. "My big concern about this is it's just the tip of the iceberg."