The image depicts a child with his arms outstretched with what appears to be snow falling on him, but the other side of the wall reveals a fire spewing ash.
The Instagram post contained a video, with the song “Little Snowflake” providing a backdrop. The video focuses on the artwork before panning away to show the town’s steel factories.
In a statement, a spokesman for Banksy said:
“Just how tight is Bxxxx? What is believed to be the graffiti artists first foray into Wales has coincided with the scrapping of the Severn bridge toll. Was the £5 charge all that was stopping him? Will we see lots more in the future?”
Ian Lewis, 55, who owns the garage containing the artwork, works for the Tata steelworks in the Welsh town, ITV reported. He told the television network that he hoped the work was a genuine Banksy creation.
"There were people coming here all night," Lewis told the BBC. "I am very pleased, I think it is a smashing bit of artwork. It is good for the town and I just want to protect it, and it is here for everybody."