Nelson fire thought suspicious

A fire has significantly damaged two vehicle testing stations in a Nelson commercial building.

Fire crews were called to Vanguard St in central Nelson about 1.30am where the fire was "well ablaze", a Fire Service southern communications spokesman said.

The damage was largely contained to the roof of the building that houses Vehicle Testing New Zealand and another testing business.

It too four fire trucks to bring the blaze under control.

The fire is being treated as suspicious and police and fire safety officers are investigating.