Arts Council England has been criticised for failing to remove a sculpture by the British artist Eduardo Paolozzi from outside Euston railway station, where it is now in the middle of a building site as part of redevelopment work to prepare for HS2.

Toby Treves, a former Tate curator and trustee of the Eduardo Paolozzi Foundation, said the council had assured him that it would transfer the sculpture to another site by the end of last year, but nothing had happened. It is understood meetings took place last week about another possible site.

The sculpture is boarded up, but Treves is concerned for its safety because two buildings around it are being demolished. “The plan for Euston station is such a radical renovation, they won’t be finished working there for eight years,” he said. “They’re knocking down the two towers immediately outside the entrance, which is where the sculpture’s sited. The main thing is, it ought not to be in the middle of a building site.”

Paolozzi, who died in 2005, is seen by many as the father of pop art in Britain. He is best known for his colourful mosaics at Tottenham Court Road tube station in London and the striking bronze depiction of Sir Isaac Newton in the forecourt of the British Library.

His huge abstracted sculpture of a head, titled Piscator, made from 16 tonnes of cast iron, has been a London landmark since British Rail commissioned it in 1980 for the Euston station forecourt.

Treves said dealing with Arts Council England had been an extremely long and frustrating process. “It was all supposed to have been moved by the end of last year, but it still hasn’t been,” he said. “The buildings are coming down around it. It had gone into some sort of bureaucratic black hole.”

The Arts Council said: “We are not in a position to comment in more detail during pre-election sensitivity, but can confirm that talks are in an advanced stage regarding the sculpture and a new site has been identified.”

The sculpture, created from mechanical and organic shapes, has an aluminium finish and measures 3.1 metres x 4.6 metres x 1.85 metres. It was inspired by Erwin Piscator, the 20th-century German Expressionist and political theatre director who collaborated with the playwright and poet Bertolt Brecht in Berlin.

Paolozzi designed it to be seen from above, from surrounding offices, as well as from the ground. He once said: “I was asked to do a large sculpture in London near Euston station and, in the preliminary paperwork, the head was called the Euston Head. The entire decision was up to me to make the head out of any material, but I have always wanted to improve on using iron as a public material.”

Treves questioned why Arts Council England preferred to keep a major piece of public art behind hoardings rather than on show.

He first raised concerns about the sculpture in the Guardian in 2016 because the foundation had struggled for years to find out who owned it, and so could not have it restored. It has suffered the effects of air pollution and traffic dirt. He said at the time: “The absurdity of this is that the foundation would willingly pay to restore and clean the sculpture, but we can’t do it without the permission of the owners.”

The foundation has since established that British Rail commissioned it and later transferred ownership to the Arts Council.

The cost of moving it would be a few thousand pounds, to which the foundation would make a contribution, Treves said: “But it’s the Arts Council’s property. They do have a duty to look after it.”