WELLINGTON, Sept 5 - The issue was raised during Monday night's TV leaders' debate and on Tuesday Ardern confirmed her position when she spoke to reporters on the campaign trail.

"There's been talk of New Zealanders being locked out of having the same access to tertiary education in Australia as Australian students have," she said. 

"If Australia makes the decision that New Zealand students can't access tertiary education the same way as Australians do, I think they would expect us to make the same move in New Zealand." 

But National leader Bill English fears it would harm the progress that has been made with the Pathway to Citizenship that would enable New Zealanders to have the same rights as Australians.

"It would be pretty silly to then slap the Australians over some deal somewhere when we've made significant progress, so we'll just continue to engage with them constructively," he said.

"They've been responsive to our approaches on those sorts of things and we'll just keep chipping away ... talk of retaliation is likely to just make it harder to make progress."

But Ardern doesn't think it would harm trans-Tasman relations.

She said the issue was particularly pertinent because Labour intended to introduce free tertiary education for the first three years of study.

However, she said education was as far as reprisals would go and there would be no retaliation for Kiwis being shut out of welfare programmes in Australia, as happens now.

"On benefits I hold a different view," she said.

"We're still fighting for New Zealanders' rights in Australia and I think we should retain the moral high ground - it's only right that if you pay taxes you have access to those benefits."