UPDATED 6.05pm: Police have arrested a man in his 30s following a fire at St Margaret’s Church, Christchurch this morning.

The man will appear in Christchurch District Court tomorrow and police are not looking for anyone else in relation to the fire.

The church was extensively damaged in the fire - to which emergency services were alerted at 5.45 this morning. 

An investigation into the fire concluded it's suspicious.

Fire Service spokesman Andrew Norris said their side of the investigation is over.

"Our specialist fire investigators worked with police on site this morning, and the fire has been determined to be suspicious."

Mr Norris said the church was well-involved, by the time crews got there.

"Currently at a third alarm, that means we've got six fire appliances and one command unit on site.

No one was hurt in the fire.

Mr Norris said the church faces an uncertain future.

"It appears that the building is possibly a total loss, so it might mean demolition of the building, as it's unsafe in its current condition."

Emergency services were called to a fire at St Joseph's Church in Grey Lynn, Auckland, this morning.

A fire communications spokeswoman said the fire, in a room on the property on Great North Road, had been extinguished.