Man sought after Wellington arson

Police investigating a suspicious fire at a Wellington self-storage unit have released CCTV footage of a person they want to speak to.

The Kiwi Self Storage building in Lyall Bay went up in flames last Friday, destroying and damaging items stored there.

Police say they are now seeking a person seen carrying a red 25-litre tank and wearing a white T-shirt over a black hooded sweatshirt, dark pants and a white cap with the words 'Vodka Cruiser' on it.

A scene examination has been completed and police confirmed the fire began after an apparent explosion in a unit.

Samples from the scene had been sent for forensic testing for any accelerant that may have been used.

There was extensive fire damage to the top floor of the building with more moderate water and smoke damage to ground floor units.

"We now believe that his was a malicious, deliberate and pre-planned arson. The occupier of the unit where the blaze started is assisting police with our inquiries but we need the public's assistance to help identify the person shown," Detective Senior Sergeant Grant Ferguson said.

"The scene examination has revealed that an explosion has occurred but we are awaiting forensic results to determine if the explosion caused the fire or the other way around.

"The fire has affected a large number of people who have lost many items valuable to them and we encourage them to contact us using the email address," he said.