The Welsh first minister has defended his government’s handling of the festive Banksy work Season’s Greetings, which is to be locked behind closed doors in a former police station after being briefly put on show to the public.

Mark Drakeford said the Welsh government had preserved the Banksy, which appeared on a steelworker’s garage in Port Talbot just before last Christmas, and continued to work on the best way of making sure it is eventually seen by as many people as possible.

In the summer the government paid for the Banksy to be moved to the former police station in the town centre and for three days this week Neath and Port Talbot opened the building to visitors.

From 3pm on Friday, however, the doors were being closed again and the long-term future of the mural remains unclear. Many people in Port Talbot have called for a contemporary gallery to be created with the Banksy as a centrepiece, and there has been criticism from some quarters that the Welsh government should be doing more to make this happen.

Drakeford said: “If it wasn’t for the things the Welsh government has done, there wouldn’t be an exhibition of any sort. This is not the end of the road. There is a bigger debate about creating a new contemporary art gallery for Wales and how that should be done. There’s a strong lobby from Port Talbot that it should be somewhere like there.

“There are other people who prefer a different model in which we’d have a dispersed collection that many people in many parts would enjoy. The future of the Banksy is caught up in that wider debate, which is why we haven’t come to final conclusions. In the meantime, we’ve worked hard to preserve that painting.”

The Banksy appeared in Taibach, close to the Tata steelworks. From one angle, it shows a child in a bobble hat with a sled, apparently enjoying a snow shower and trying to catch the flakes on their tongue. But from another it becomes clear that what is falling on the child is ash.

Banksy confirmed the work was his by releasing a video of the mural accompanied by the Christmas song Little Snowflake. The camera rises above the garage and shows Port Talbot’s rooftops and the billowing chimneys of the steelworks and other industrial buildings.

The art dealer John Brandler bought the Banksy from Ian Lewis, who owned the garage and thus the artwork, for a six-figure sum and promised it would stay in Port Talbot for at least three years.

Brandler is frustrated that the immediate future of the piece remains unclear. He said: “It is my guess that the authorities are saying we opened it to the public but only ‘X’ people came so there’s no point in opening a museum. I hope for the people of Neath Port Talbot I’m wrong.”