Leader Roger Lawrence fears an "asset strip" of the shopping complex after it was put up for sale.
His fears centre on Rock Form, which is possibly worth millions and was donated to the city centre complex by the Mander family in 1968.
The bronze 9ft sculpture made by Barbara Hepworth is one of only six of its kind in the country and was recently removed from its normal position on the ground floor as part of a multi-million pound redevelopment of the centre.
Councillor Lawrence said: "The work of art was apparently taken away for 'safe keeping.' Despite requests from concerned members of the public and local councillors, no time scale has been given by the owners for its return to public display or any reassurance given that it will not be put up for sale. This attitude suggests asset stripping. A similar piece recently sold for £5 million."
He said the familiar piece was well-loved in the city and he was worried about a "lack of transparency" from Mander Centre bosses.
"The centre and sculpture are currently owned by MCI Ltd and Royal Bank of Scotland. The Mander Centre was this year put up for sale by its owners and the sculpture was removed at the same time," he added. "I have now written to the Chancellor George Osborne urging him to step in and stop any proposed sale of the piece of art."
Mander Centre manager Nicholas Pitt replied: "The people who have contacted me over this issue have certainly shown a great deal of passion for the piece in question. They have all been very polite and I have passed on all their comments to the people to whom I report. However, I have no personal influence on what happens to the statue."
He said he could not add further to a previous statement in which he explained: "The majority of the redevelopment will take place on the lower level, where the sculpture was located. As such, the current landlords were advised by insurers that this valuable piece be removed and stored securely off-site. No further decisions have been made concerning the sculpture, which in my view is a particularly beautiful piece."
The current redevelopment of the shopping centre includes the creation of a new Debenhams store that is expected to create at least 120 new jobs.
City leisure chief Councillor Elias Mattu added to the Rock Form issue by saying: "It is well-loved and as familiar to the people of Wolverhampton as the 'man of the horse' statue. I have explained to concerned residents that the council does not own it. However, we strongly believe it was the intention of the Mander family that the sculpture remain in the city and be enjoyed by all its residents."