However, Mr Alderton also indicated that not all complaints received so far were about Countdown but that company's practices remained the focus of the inquiry at this point.
The local supermarket industry is dominated by a duopoly comprised of Countdown and its Australian-owned parent Progressive Enterprises, and NZ-owned co-operative Foodstuffs whose members own New World and Pak'nSave stores.
Food and Grocery Council chief executive Katherine Rich later told the Herald she didn't know what had been shared with the commission about operators other than Countdown. "But certainly some of our members have raised the issue that at the moment the focus is solely on one part of the sector when in fact some of the discussions are relevant to the other half. What the Commerce Commission investigation has done is raised a wider discussion about supermarket behaviour and business culture," Ms Rich said.
"I don't know enough about the commission's process about whether they can widen it out or not. It would be up to the commission depending on information provided to it."
Meanwhile, Mr Cosgrove also asked Mr Alderton whether he could confirm that "a complaint of a $2 million retrospective payment was made to the commission" and that "once it reached your desk, that complaint effectively vanished because Progressive went to the supplier and basically said it was a big mistake, that they didn't want $2 million?"
Mr Alderton said it would be inappropriate to comment given the commission's ongoing investigation.
Mr Cosgrove would not repeat the claims his questions were based on outside of the committee room, where he had the protection of parliamentary privilege.
Asked about the claims raised by Mr Cosgrove, Progressive Enterprises managing director Dave Chambers said: "We continue to reject the allegations made about our business. It's disappointing that a month down the track we're still no clearer on what the alleged misconduct is; we haven't seen anything to support the claims made under parliamentary privilege and we don't have any further detail on what the Commerce Commission is investigating."
A narrow majority of New Zealanders believe Labour MP Shane Jones is right in his claims the Countdown supermarket chain has been bullying New Zealand suppliers, a Herald-DigiPoll survey suggests.
A month ago, the Commerce Commission confirmed it was investigating Mr Jones' allegations Countdown was demanding retrospective payments from suppliers or threatening them with having their products blacklisted.
Countdown's parent company, Australian-owned Progressive Enterprises, denies the allegations. The Herald-Digipoll survey asked 750 New Zealanders who they believed. Just over 51 per cent backed Mr Jones while just 20.4 per cent believed Countdown.
"The reason I think people have warmed to my message is that it's on song with what is important," Mr Jones said. "This was always about fairness. This was always about Kiwis getting a decent shot. The Aussies have been closing us out.
"I look forward to Labour replicating those results in an electoral sense."
Countdown, which yesterday repeated its denial of Mr Jones' allegations, refused to comment directly on the poll result, saying: "Right now we're just focused on what we do everyday, and it's not appropriate for us to comment any further."
