The ambulance service said two people were in critical condition and four others seriously hurt, with the rest moderately injured, after the crash in the Waikato region of the North Island.

The cause of the three-vehicle collision was not known. It happened on a straight stretch of highway during good weather conditions.

New Zealand's police confirmed that a small bus carrying 11 international tourists and their driver was involved in the crash. There were three people in the other two vehicles.