Police hunting for thieves who stole a Henry Moore sculpture worth £3m fear it could be melted down and sold as scrap.
Henry Moore's Reclining Figure is considered a "national treasure"
The bronze Reclining Figure was stolen by thieves from the grounds of the Perry Green estate in Much Hadham, Hertfordshire, on Thursday evening.
CCTV cameras filmed the three raiders as they used a crane to lift the two-tonne piece on to a lorry.
The officer leading the hunt said the sculpture would only have a scrap metal value of about £5,000.
The Henry Moore Foundation, which owns the sculpture and has offered a "substantial" reward for its return, has begun a review of its security.
Chief Inspector Richard Harbon said police classed the sculpture as a "national treasure" and detectives from Hertfordshire were working with the Metropolitan Police's Fine Arts Squad.
He added: "It is a nationally-renowned sculpture and very, very difficult to get rid of.
"So, obviously, we are looking at all the possibilities, right from scrap metal right up to fine arts theft.
"This is not opportunist theft. These are people who knew what they were doing, knew what they were after. A very, very audacious theft."
A police spokesman said one of the two vehicles used in the raid was a Mercedes flat-bed lorry, possibly red, with a "hi-ab" lifting crane on the back.
The other was a Daihatsu four-wheel drive with spotlights at the front.
One of the three suspects wore a hooded jacket and one a baseball cap.
Foundation spokesman Gareth Spence said: "It is quite a daring thing to do, and it will cause a reassessment of our security process.
"Obviously, we are very upset and disappointed.
"The theft alone has caused a great deal of upset, but the thought of it being melted down is ever more so.
"It is very difficult to express the emotions of the foundation at the moment at the prospect of that."
Considered by many to be the most outstanding British sculptor of the century, Moore died at 88 in August 1986.
A few years before his death, Moore gave the whole estate of Perry Green to the trustees of the Henry Moore Foundation.
Its aims were to conserve the work and reputation of the artist and the setting in which the work was created, and to generally assist the arts and, in particular, sculpture within the cultural life of the country.