Museums across the country have been put on alert after professional thieves stole Japanese artwork from Birmingham's main gallery.
Two men and a woman raided cabinets at the city centre Museum and Art Gallery to seize the ornate wooden and ivory carvings which date from the 12th Century.
The theft follows a number of high-profile raids on the museum and prompted a fresh row last night over security.
Procedures were reviewed after previous thefts and museum officials have already launched an inquiry after the latest embarrassing breach.
The stolen items, known as Netsuke, form part of traditional Japanese dress and are worth up to a total of pounds 40,000. They have been part of the museum's collection for over 100 years.
The 20 pieces were taken from a glass cabinet in the gallery and police are studying security videos in an attempt to capture the thieves.
A spokeswoman for the museum said they were disappointed the display cabinets had been opened and a review of security had already taken place.
The cabinets, which are of an approved security standard for museums, are designed for visitors to examine objects closely.
A spokeswoman for West Midlands Police said they were treating the theft as an isolated incident and were not linking it with any other art raids across the country at this stage of the investigation.
Detectives are anxious to speak to two men and a woman who were seen behaving in a odd manner as they were leaving the building last Wednesday.
She said: "It is thought the three offenders forced a display cabinet with an unknown instrument and removed the figures before leaving the building."
It is believed the thieves were professionals who deliberately targeted certain pieces from the museum's collection.
Netsuke are highly decorative carved and wooden ivory toggles which form an important …