West Coast police and Fire and Emergency NZ are investigating two suspicious fires which may be arson in Greymouth and Westport at the weekend.
It follows the arson of the Church of Jesus Christ of the Latter Day Saints at Karoro a fortnight ago.
Late on Friday night, a police patrol spotted a Thompson Street house on fire. It is now being treated as arson by police following a preliminary investigation at the weekend.
Greymouth fire chief Lee Swinburn said they were called at 10.30pm to find the front part of the house in smoke.
The underlying fire was quickly contained, with the brigade on the scene for about an hour. The house itself did not sustain substantial damage and was essentially saved.
"No-one was home, police and fire investigators are looking into it," Mr Swinburn said.
Meanwhile, the Westport Volunteer Fire Brigade was called to a Brougham Street residence at 11.45pm on Sunday after a neighbour awoke to a dog barking and the sound of "popping" and looked out to discover the fire.
Fire chief Alan Kennedy said the front of the house - the lounge area and a bedroom - was gutted.
"The front of the house was very damaged," he said. "We think it is suspicious."
The Westport, Granity and Waimangaroa brigades were at the scene for about three hours.
No-one had been living in the house and it appeared the previous resident was in the process of moving out.
Mr Kennedy said the bulk of the house had been saved but given the circumstances, it seemed suspicious and the West Coast fire safety officer had been dispatched to begin an investigation.
Acting Sergeant Mat Wood, of Greymouth, said that following preliminary investigation at the weekend the Thompson Street fire was "definitely an arson".
"We were actually in the area when it started," he said.
Police deployed its tracker dog team on Friday night and inquiries by the CIB are ongoing.
Meanwhile, West Coast CIB staff had been deployed to Westport to investigate the latest fire, Mr Wood said.
Anyone who observed suspicious activity or had information on either of the fires are urged to contact the police by calling the local station or anonymously through Crimestoppers on 0800 555 111.
