A police and fire investigation is underway at the botanic gardens in Christchurch.

A police spokesperson told chrislynchmedia.com officers were alerted to a fire at around 7:40am.

It happened at Cunningham House, which is closed for restoration.

A video sent to Chris Lynch Media show burnt parts of plastic wrapping, with police confirming that the building has been damaged by fire.

The police spokesperson said there are no reports of injuries.

At this stage police are treating the fire as unexplained and are working to determine the circumstances.

The spokesperson said members of the public may see an increased police presence in the area while enquiries continue.​​​​​​​​​​​​​​​​

While the fire is being treated as unexplained, another emergency personnel said they were leaning more towards the fire being arson.