The Ministry for Primary Industries (MPI) has shut the door on exporters who haven't registered their brands sending infant formula to China.
The ministry set a deadline of Thursday last week for exporters to sign up to a new brand register.
Chinese authorities have asked for brand information to be added to all the export certificates that MPI issues for shipments there, because of concerns about infant formula being sold under false labels in China.
Chinese consumers and regulators have been questioning the authenticity of many brands of milk formula being sold there.
MPI director of market assurance Tim Knox says 30 New Zealand exporters have provided information on their formula brands.
He says they'll need to provide more detailed information including copies of the actual labels approved by Chinese regulators with translations by 6 July.
Mr Knox says from now on MPI will not be able to issue export certificates for any unregistered brands of infant formula going to China, although it is prepared to work with any exporter who, for valid reasons, finds it difficult to comply with the deadline.
Brand information provided on health certificates and kept in MPI databases will help the Chinese authorities to identify brands that have legally entered the country and those that have been falsely labelled as coming from New Zealand.