An expansion of the free school lunches scheme has been welcomed by principals who say they expect more students to turn up without food after the Covid-19 lockdown.

Budget 2020 included $221 million to rapidly scale up the free lunch programme from 8000 children to 200,000 children at disadvantaged schools by mid-2021.

Pat Newman, principal of Hora Hora Primary School in Whangārei, said schools in hard-up areas would be "leaping up and down" to be included in the scheme.

"It was already needed," he said. "And it is very, very clear that we are going to have much higher employment and it will be needed even more when we go back."

His decile 1 school already provided breakfasts and lunches to around 10 per cent of 400-student roll with the help of local businesses.

"It makes a huge difference," he said. "It calms this place down. The kids want to learn. You don't have lunches stolen, You don't have kids threatening others because they're hungry. They are kids that content and happy."

Kimi Ora Community School in Flaxmere, Hastings, is one of the schools already being funded to provide free lunches.

"It has a huge impact on kids' learning and just on kids' mental wellbeing," said principal Matt O'Dowda.

Because all students at the primary school took part, it removed the stigma of poverty: "It just levels the playing field." And it had reduced truancy because families of children used to be embarassed to send their children to school without lunch.

Prime Minister Jacinda Ardern, who also holds the Child Poverty Reduction portfolio, said a full stomach made all the difference to a child's learning.

"Providing a free and healthy lunch at school is one way to help make New Zealand the best place in the world to be a child and to make that difference immediately," she said.

The previous National government also supported free meals in schools and invested in the Kickstart programme run by Sanitarium and Fonterra.

National was against a universal rollout of the scheme. Leader Simon Bridges said today that the message to parents of children getting free lunches in schools was that they didn't need to provide their kids with food.

O'Dowda rejected this argument.

"It's never a 5 year-old's fault that they don't have food. Do we punish the kids for things that other people are responsible for?"

Education Minister Chris Hipkins said the size of the expansion meant work would be scaled up during Term 3. Around 21,000 students in Years 1-8 will get lunches by the end of this year.

Hipkins estimated about 2000 jobs in local communities would be created by expanding the programme.

Another $32 million would also go towards responding to the increasing demand and pressures on foodbanks created by the Covid-19 crisis.

A new bulk food distribution - dubbed the New Zealand Food Network - will be set up to support food banks and other community food providers.