A man has been charged after allegedly using explosives to start a fire at an abandoned house in Dunedin this week.

Police said it was one of three suspicious fires in the city in the space of several hours early on Tuesday morning.

The 48-year-old man faces charges of wilfully damaging a property by explosive in relation to just one of three fires.

All three were being treated as suspicious.

“A vacant building and 30x30m of pine trees were ruined in the other blazes," police said.

A Fire and Emergency spokesperson earlier said they were notified of the first fire at a vacant building well ablaze on Harrow St, around 11.30pm.

Four fire trucks and a ladder truck arrived at the scene.

The fire was contained after midnight and extinguished at 3am, the spokesperson said.

Fire and Emergency received multiple calls of another fire at a Central Dunedin house around 12.30am.

Concerns that people were in the house were quashed after it was found empty, said the spokesperson.

Five fire trucks and a command unit contained the fire at 1.50am.

Around 1.30am, firefighters responded to reports of trees on fire near Otago Pistol Club in Waldronville.