Andrew Little says another bad season for dairy farmers could cause New Zealanders to lose some of the country's best agricultural land to offshore buyers.
The Labour leader said Fonterra had offered interest-free loans to some struggling farmers.
On the Q&A programme, he said banks had told him they'd help farmers for one tough season, but beyond that there were uncertainties.
"There is a crisis in dairy...we do have some tough times ahead." He told TV One a combination of the Government, farmers and banks needed to work together to address the problem. Mr Little said "the biggest threat" to farmers would arise when they couldn't even afford to keep their land.
He said if dairy farmers had to start selling land, people with the money to buy that land would be offshore buyers, such as the Americans and Chinese.