The country splitting into two alert levels may cause problems for businesses reliant on supplies

More businesses across New Zealand can now operate in level three -- but some of them use manufacturers in Auckland, who can't operate in level four.

The Employers and Manufacturers Association says it'll lead to significant issues for businesses who can't get the raw materials and parts they need.

Head of advocacy and strategy Alan McDonald says the Government's being firm that non-essential businesses in Auckland still can't operate, even to service those outside.

He says you can sort of understand the hard line, but it doesn't solve the problem for businesses who won't be able to operate.