WELLINGTON (AFP) - Two people have died after a bus carrying a student band from Tonga crashed 100m down a bank while they were heading to a Christmas Day service in New Zealand, police said on Sunday (Dec 25).

More than 40 people were injured when the bus ploughed through a barrier and rolled down a steep bank late on Christmas Eve about 30km from the resort town of Gisborne, on the east coast of the North Island.

The body of one person was found soon after the crash and the second body was recovered in a later search of the wreckage.

Facebook posts identified the passengers as a brass band comprising students and teachers from Mailefihi Siulikutapu College on Vavau Island in Tonga.

Police initially said 46 people were on board, but after the discovery of the second body they said the numbers were yet to be confirmed and they were working with the survivors to make sure everyone was accounted for.

Ambulance staff said 41 people required treatment and 27 were taken to hospital.

"The passengers are believed to be mainly Tongan school students, who are visiting New Zealand to fundraise for their school in Tonga," the police said in a statement.

"The group were travelling to Gisborne where they were due to perform as a band on Christmas Day."

Local media reports said the group were to have performed at Christmas church services and passengers not requiring hospital treatment were being cared for by the local Tongan community and Methodist Church.