New Zealand trainers can continue to work their horses while racing is shut down under government guidelines.

From midnight Wednesday, New Zealand will move to COVID-19 alert level 4 with only essential services permitted to operate.

NZ Thoroughbred Racing has issued a statement outlining conditions.

"Our advice from the Ministry for Primary Industries confirms that training centres, training stables, agistment properties and stud farms where horses are in containment are considered essential services under animal welfare considerations," NZTR said.

"Businesses with more than five people (including the owner) working at each business site, or who cannot achieve social distancing between staff, are required to register.

"The businesses will need to answer 11 questions to provide assurance they have a plan and process to manage infection risks."

NZTR said it would issue detailed protocols on Wednesday and a template to assist trainers with the necessary paperwork.

New Zealand racing will be closed for at least four weeks.