One of New Zealand's largest transport companies has been charged after its bus careened down a 100-metre bank near Gisborne on Christmas Eve 2016, killing three and injuring dozens more.

The Herald can reveal that Ritchies Transport Holdings Ltd (Ritchies Coachlines), along with the driver of the bus, now faces being held criminally liable over the crash.

The charges were laid by WorkSafe at the Waitakere District Court on December 21, just days before the one-year anniversary of the crash on State Highway 2, south of Gisborne.

The bus was carrying 53 people from Tonga's Mailefihi Siu'ilikutapu College brass band when it plunged down the bank about 10.30pm.

Eleven-year-old Sione Taumalolo, and Talita Moimoi, 33, were killed.

The band's head tutor Leotisia Malakai, 55, described by her cousin Sinai Meafoou as a "beautiful and kind-hearted lady", died eight days later of head and internal injuries.

Sione Taumalolo, 11, and Talita Moimoi, 33, died in the Christmas Eve crash. (Photos / NZ Herald)

Tevita Lokotui, a prefect at the college who played tuba in the school band, also lost his left leg at the knee as a result of the crash.

Siokatame Tupou, the brass band's conductor, was also seriously injured.

The band was in New Zealand as part of a fundraising trip, and was travelling to perform at Gisborne's Wesleyan Methodist Church on Christmas Day.

Tevita Lokotui lost his left leg at the knee. (Photo / Paul Taylor)

Ritchies' depot manager for its West Auckland division, Tim Briscoe, said he was aware of the charge but wouldn't comment about the case while it was before the courts.