The Prime Minister is defending his proposed immigration crackdown, amid a flurry of negative feedback.

Changes to the skilled migrant visa would require workers to earn a minimum of around $49,000 and require them to leave for a year, after three years.

Bill English said the hospitality, trucking and horticulture sectors told them parameters are too tight, making it harder for businesses to get the workers they need.

He told Mike Hosking National will tweak its proposal but said immigration changes are still necessary.

"We don't want big sectors of the economy relying on an inflow of people from overseas," he said.

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