Auckland City Mayor John Banks has admitted claiming $438.80 in entertainment costs after issuing a Super City mayoral campaign bulletin saying he had "never charged a sandwich, lunch or coffee to the ratepayers of Auckland".

And he broke council rules when office staff sought reimbursement for the entertainment against a bill for private use of his cellphone instead of making an expenses claim.

Last night, Mr Banks said it was a genuine mistake to say he had never charged anything to ratepayers outside work in the Town Hall, and he would run a correction in his next online campaign bulletin.

"I completely forgot about any of that [entertaining]. I'm not making any excuses. I'm putting my hand up.

"On this one occasion, that amount of money, $438, was offset against the money I owed the council for private use of my cellphone.

"I had never seen the prescribed form that you have to claim on if you want any money back, until Friday. I have never made an application, and I have never made a claim."

Under an agreement with the council, Mr Banks reimburses the city 15 per cent of his mobile phone costs to cover his private calls.

The $438.80 claim covers four occasions - entertaining the United States Ambassador at Euro Restaurant on the waterfront for $215.50, catching up with arts patron James Wallace at Frasers cafe in Mt Eden ($23.80), discussing the Peter Blake memorial with businessman John Street at the Stamford Plaza Hotel ($44) and having lunch with Britomart developer Peter Cooper at the Northern Club ($155.50).

Mr Banks, who has sniped at Super City mayoral opponent Len Brown over "reckless spending behaviour on ... ratepayer-funded credit cards", said he normally did not claim expenses for items such as lunches and taxis.

And he did not claim for a second home landline, a broadband internet connection, a home computer and printer to which he was entitled and which are worth about $2000 a year.

Mayoral office figures also show Mr Banks entertained Rodney Mayor Penny Webster and her husband and High Court judge Mark Cooper and his wife in the council box at the ASB Classic tennis tournament for $237.60.

Mr Banks said it was absolutely appropriate to entertain the four guests and he would have paid but did not have any money. The bill went on the credit card of his mayoral assistant.

Mr Brown, who has faced intense political and media scrutiny over his credit card expenses, did not wish to comment directly about Mr Banks' expenses.

"It's up to John to justify his comments to the public," he said.

Figures also show that Mr Banks, who has made a virtue of being frugal with ratepayers' money, has exceeded the mayoral office budget of $570,865 by $41,606 over the past year.

The biggest problem has been temporary staff costs, which jumped from the budget of $10,000 to $88,372, and catering charges, which have gone from $26,006 to $36,691.

Mr Banks' weekly breakfast meeting with 25 senior staff and councillors costs $235.50, regular fruit bowls cost $20 and morning teas and working lunches generally cost less than $100.

The most expensive office function in the past year was $1400 for a morning tea medal ceremony for the New Zealand Army.

Mr Banks said he had had a lot of turnover in temporary staff.

But he was spending about $100,000 a year less than his predecessor, Dick Hubbard.

Dining at Euro restaurant with the United States Ambassador.

Lunch with developer Peter Cooper at Northern Club.

Peter Blake memorial talks with businessman John Street at Stamford Plaza Hotel.

Coffee with arts patron James Wallace at Frasers cafe.

Total: $438.80
(offset against cost of his personal cellphone calls).