A treasure trove of rare and valuable Aboriginal art has been found languishing in the back of a school store cupboard in Canberra.

The bark paintings, which are estimated to be about 25 years old, were unearthed during a spring clean at Dickson College in the Australian capital.

The artworks were found by stunned staff members who had been emptying parts of the school in preparation for renovations.

The 12 paintings, which were well preserved in the dark and dry conditions of the cupboard, were created by well-known indigenous artists from Arnhem Land in the Northern Territory.

It is believed that they were bought by the school to be used in Aboriginal studies classes.