Parents who are dissatisfied with the new school lunch programme should "make a marmite sandwich and put an apple in a bag," Prime Minister Christopher Luxon said.

It comes after numerous problems were reported with the school lunches including most recently, plastic melted into the food.

Luxon first made the comments during an interview with Newstalk ZB on Tuesday, saying parents who were unhappy with the lunches should pack them themselves.

"If you are unhappy with it, for God's sake, go make a Marmite sandwich and put an apple in a bag just like you and I had."

Speaking to reporters ahead of National's regular Caucus meeting, Luxon said parents have the choice to make their kids a sandwich and chuck an apple in a bag if they don't like what is on offer through the programme.

It is for the minister, Associate Education Minister David Seymour, to negotiate what is offered - but an alternative could be a sandwich and piece of fruit being provided.

He said he'd rather have parents take responsibility for feeding their children rather than the government.

However, he did acknowledge that some of the lunches and deliveries weren't meeting the standard and were not "up to scratch".

"I would rather the state didn't have to do so. It should be a parental responsibility," Luxon told Newstalk. "But the fact is that kids are actually coming to school with no lunch. I'm not willing to let them go hungry."

Talking to reporters later, he acknowledged not everyone can afford to make lunches but said for many a loaf of bread, some jam, and a piece of fruit isn't "rocket science".

Labour leader Chris Hipkins told RNZ a healthy and nutritious meal for school children can be a sandwich and a piece of fruit - often that is what was served during the old programme under his government.

He isn't set on daily hot meals being provided, but added a mixture of cold and hot meals often worked well for schools in the past.

Luxon had previously said he expected Seymour to give the school lunch programme his "full attention" after Checkpoint revealed concerns from west Auckland schools about the lunches being late, inedible, repetitive, or failing to meet dietary restrictions.

Speaking to reporters in Vietnam last week, Luxon described them as "teething problems".

"David Seymour will work his way through those issues and he's minister responsible for it and I expect he will and I know that he's well aware of the challenges and working his way through what have been some teething issues up front but he will work his way through that."

He said Seymour was "accountable for delivering" and Luxon had no doubt he would be able to.

The two had discussed the problems, Luxon said. "I think he knows exactly what needs to happen."

While parts of the programme were being delivered well there had been problems with being on time and meeting the contract, Luxon said.

"David will be giving it his full court and full attention and I expect him to do so."

Stanford won't say if she backs Seymour to fix school lunches

A planned meeting between Education Minister Erica Stanford and Seymour never went ahead after party Caucus gatherings this morning ran late.

Speaking to reporters ahead of the meeting, Stanford would not say if she had confidence Seymour could fix the lunch problems.

She had put school lunches at the top of the agenda for her meeting with Seymour - a regular one between the pair - but that meeting has had to be rescheduled.

It's unclear whether there will be time no Tuesday, but Stanford has asked for the meeting to be rescheduled at the "earliest convenience".

Carmel Sepuloni last week called for Seymour to be sacked for delivering a lunch programme that is a shambles.

"He's the one that turned this programme upside down. It was working really well prior to David Seymour's intervention," the Labour party deputy leader said.

"But I will put on the record too that the primary Minister of Education is Erica Stanford, she needs to stand up, take over and fix this mess because clearly David Seymour is not capable of doing so."

In a statement, Seymour said the issue was being politicised.

"The revamped school lunch program will save $170 million dollars when it is extended to all schools. At the same time it achieved 100 per cent on time delivery yesterday, and many students and principals are praising the new meals as being better than the old".

Four food safety investigations underway into scheme

Meanwhile, the Ministry for Primary Industries has launched an investigation into School Lunch Collective meals served to children with plastic packaging melted into the contents, one of four food safety investigations underway into the troubled scheme.

The Collective - which provides most of the country's school lunches - has been plagued with problems since it replaced local providers this year.

Murchison Area School principal Andy Ashworth said its certainly not the first problem he'd had with the School Lunch Collective programme.

He has avoided criticising the quality of the food, wanting to give the companies "a bit of leeway", but said even before the meals with baked-in plastic, the school had an array of issues.

Ministry of Education hautū (leader) operations and integration Sean Teddy called the situation "entirely unacceptable", and said concerns raised by the school on behalf of their students and community were "completely justified."

Teddy said the Ministry took all food safety issues very seriously, and was seeking a full account of how the problem had occurred.

He said it was yet to be determined if the food safety issues amounted to a material breach of the Ministry's contract with the School Lunch Collective, but if one was found, a written breach notice would be sent.

The coalition government announced plans to scale back the cost of the Ka ora, Ka ako free school lunch programme in intermediate and high schools in early May 2024.

In unveiling the new menu in October, Seymour said the reboot would save more than $130 million a year with items including butter chicken curry, chicken katsu, lasagne, chicken pasta salad and wraps at a cost of $3 each.

Around 230,000 students rely on free school lunches.