Actew Water managing director Mark Sullivan told staff in an email on Thursday that the party was cancelled in part due to ''unfair scrutiny both organisations have recently come under regarding expenditure and staff benefits''.

A ''bitterly disappointed'' Mr Costello said he made the decision on Thursday - the same day The Canberra Times asked ActewAGL to detail various expenditures by the power provider including the cost of the dinner.

Mr Costello said he had not been prompted to move by the questioning or by outgoing chairman John Mackay detailing in The Canberra Times last week expenditure by the utilities including that the staff dinner was ''like a night at the Logies''.

Mr Costello also distanced himself from Mr Sullivan's reference to the ''unfair scrutiny''.

''No, no. I don't know what Mark said. I'm just saying what I've said. Mark didn't make the decision, I made it and he said he wasn't going to disagree with it,'' he said.

Mr Costello maintained the dinner and the expenditure on it was becoming a ''negative'' and he did not want the staff to have to defend their involvement in it.

''I can see people saying at barbecues, 'Oh, you're ripping us off'. But whatever I say, and whatever the reality is, everyone thinks it is adding to their electricity bills and it's not,'' Mr Costello said.

''I'm not going to inflict this negativity on my staff. They've got better things to do with their lives than go around defending themselves from these kinds of accusations.

''I'm not making judgments about whether it's fair or unfair, the attacks. They're there and I think they're only going to get worse.''

The party cancellation comes after a public outcry over Mr Sullivan's under-reported income of $855,000 and letters to the editor since the Mackay interview critical of Actew Water and ActewAGL's spending priorities.

Between 1400 and 1600 people - staff and their partners - have attended the end-of-year party at Exhibition Park in Canberra to reward them for the year's work and distribute awards.

The next one was to be held on November 15.

A separate Christmas party for the children of Actew and ActewAGL staff will continue to be held in

December at a cost of $40,000. The staff dinner was started about eight years ago and had initially been held in June. Mr Costello said the dinner cost ''a bit under'' $300,000 which he believed was just reward for staff delivering the cheapest and most reliable electricity in the country.

''I think it's been a fantastic and totally justified occasion,'' he said.

When asked why the event shouldn't then continue, Mr Costello again repeated it was becoming a negative.

He also denied it was an attempt to shift public criticism of the utilities' management and board on to the on-the-ground staff.

''I don't mind people attacking me, it's part of life but I am concerned about the reputation of the organisation and about the staff themselves. They identify very, very closely to this place. They see it as their family and they don't like it when it's attacked like this.''

He said an alternative celebration would be considered such as a staff breakfast but he also wanted to acknowledge the sacrifices made by their partners.

''Partners of many of these staff have to put up with them being on call and being out in the middle of the night and working on weekends and public holidays,'' he said.

''I feel distressed and deeply apologise to the staff for having to make the decision but I think it's in their best interests.''

He said there were also concerns about the number of people at an event with alcohol and getting them home safely but claimed that was not ''the dominant factor'' for cancelling the event. ''The thing that tipped the balance was this has moved from something that was a positive to an atmosphere where all we'll do is get bagged for this,'' Mr Costello said.

Senior Commissioner Malcolm Gray from the Independent Competition and Regulatory Commission also told The Canberra Times this week that customers could be confident that corporate spending by the utilities was not affecting electricity prices.

Costs such as salaries and other corporate expenditure by ActewAGL did not have an impact because the data used was the market costs confronting all electricity retailers.

''In the case of electricity prices, we can be as confident as you can be that the costs we are factoring into the price determination are the costs they would actually occur in providing the service and wouldn't include any unreasonable or undue costs,'' Mr Gray said.

The commissioner said when it came to water prices, it was ''unlikely any of this [corporate] stuff is going to make its way in there and if it does, it's going to be on such a small scale as to make no material difference to the cost outcome.''

However, Mr Gray said there was a whole other issue that was not within the remit of the commission about whether the money spent on corporate largesse should instead be returned to the shareholders of the utilities, including the ACT government.

Mr Sullivan accepted a $140,000 pay cut in April after the controversy over his $855,000 pay packet.

The under-reporting of Mr Sullivan's salary, by $234,000, led to the resignation of Actew Water and ActewAGL chairman John Mackay.

Mr Sullivan told staff he was sorry the annual dinner had been cancelled.

"There are a few factors that contributed to Michael's decision, such as the ongoing safety concerns due to the risks of having such a large function at which alcohol is served, as well as the unfair scrutiny both organisations have recently come under regarding expenditure and staff benefits," he wrote.

"Although there will be no staff dinner this year please do not feel disheartened.

"I appreciate and greatly value the work of everyone within our organisation, and promise you we will find other ways to celebrate our successes throughout the year."