Detectives from a specialist police squad investigating art and antique crime have been reassigned to the Grenfell Tower investigation, prompting fears it could close altogether.
Three officers from Scotland Yard's Art and Antiques team were "temporarily" parachuted in to assist the massive operation following the west London inferno, police said.
But Vernon Rapley, who headed the Metropolitan Police unit for almost a decade, said he had not been given assurances the officers would return to their roles.
The former police chief added he was "worried that the closure of the unit is now being considered".
Specialising in tackling the theft and fraud of cultural items, the unit is responsible for the London Stolen Art Database - cataloguing the details of 54,000 stolen works.
Mr Rapley told The Art Newspaper: "I am very concerned that the Metropolitan Police is unable to give assurances on when the three detectives who have been temporarily reassigned will be returned to the unit."
He said the capital needed a "dedicated art squad", adding: "Losing it now, when cultural heritage is under threat in so much of the world, would represent a very serious loss."
Units from across the force have been drafted in to help the Grenfell Tower probe after at least 80 people died when fire swept through the building in June.
Police are expected to continue the painstaking process of recovering evidence from the block's blackened skeleton until the end of the year.
The Royal Borough of Kensington and Cheslea, which owned the tower, and the Kensington and Chelsea Tenant Management Organisation, which ran it, are being investigated over potential corporate manslaughter offences.
A spokeswoman for the Metropolitan Police said: "A total of three detectives from the Art and Antiques Unit have been temporarily transferred to the team of specialist investigators involved in the Grenfell Tower fire investigation
"The investigation into the fire is one of the largest in the Met's history and involves the use of detectives from a range of different units.
"The Met has liaised with key partners of the Arts and Antiques Unit, and is maintaining ongoing relationships with them in this interim period, and will continue to investigate any allegations of crime related to art or antiques, which can be reported by calling 101 or, in the case of an emergency, by calling 999."