The theft of a painting and cash from a donation box at Nelson's Christ Church Cathedral is a breach of trust, the cathedral's dean says.

A painting of the destroyed ChristChurch Cathedral in the aftermath of the February 22, 2011, earthquake was stolen from Nelson's Christ Church Cathedral at the weekend.

Police spokeswoman Barbara Dunn said the painting, valued at $450, was taken on Sunday between noon and 4pm from a stand inside the cathedral.

Cash was also taken from the donations box.

The cathedral was open at the time.

The original painting measures 50cm by 40cm and was given to the cathedral.

Dean Nick Kirk said cash had been disappearing from the cathedral's donations box during the past couple of weeks.

"The cathedral is a place of trust really. That's why we leave the doors open during the day. It's sad that has happened. We don't want to have to close the doors."

Dean Kirk said the painting was donated by a parishioner and was used to draw awareness to ChristChurch Cathedral's plight and as a stimulus for prayer.

Anyone with information about the painting's whereabouts should phone the Nelson police, 03 546-3840.