City council Leisure chief Councillor Elias Mattu said residents had contacted him asking where the Rock Form sculpture – said to be worth £1m – had gone.
The sculpture was removed last month ahead of the shopping centre's multi-million pound redevelopment.
Bosses said then no decision had been made as to its future, and that remains the case.
It is one of only six of its kind in the country and was donated to the Mander Centre by the Mander family in the 1960s.
But Councillor Mattu expressed concern as to its whereabouts.
Councillor Mattu said: "I have been approached by numerous members of the public about the sudden disappearance of this sculpture.
"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.
"For that reason I am calling on the current owners to either return the sculpture immediately, or publically reassure the residents of our city that it will not be sold for their personal profit by providing them with the date we can expect to see it back on public display again."
Popular sculpture Rock Form, by Barbara Hepworth, has been in the centre since it opened in 1968.
In recent weeks the piece has been taken away from its usual home on the ground floor of the centre with bosses saying they have been advised by insurers that the piece should be removed and stored away from the centre, ahead of its multi-million pound redevelopment.
The centre's £30m redevelopment was recently given the go-ahead by planning chiefs.
The redevelopment, which includes the creation of a new Debenhams store, was unanimously backed by councillors at a meeting.
Mander Centre manager Nicholas Pitt reiterated that no decision had to made as to where the sculpture would go as part of the redevelopment.
He said: "The majority of the redevelopment will take place on the lower level, where the Barbara Hepworth 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 Barbara Hepworth sculpture, which in my view is a particularly beautiful piece."
The bronze 9ft sculpture contains within its square base a time capsule containing items donating by Wolverhampton children and traders.
It was last removed in 2002 - and refurbished - when the centre was given an £18m revamp.
The sculpture was constructed in 1964 and one of the six was last year allocated to the Scottish National Gallery of Modern Art.
The new Debenhams store in the centre is poised to create at least 120 new jobs in the city.