Gloucestershire Police said they had received allegations that Opus Fine Art in Stow-on-the-Wold had been "dishonestly retaining or selling" art.
The gallery deals in works by high profile artists including Damien Hirst.
A police spokesman said investigations were ongoing to establish ownership of the seized property.
The Independent newspaper reported the owners, Donald Smith and Emma Poole, were believed to have moved to the south of France.

25 October 2013 Last updated at 09:08 BST
The mummies of an adult and a child were found at an old religious site in the capital Lima.
Experts also found other offerings including the remains of guinea pigs and jars with cat designs.
They're being described as one of the most important finds in more than 30 years.
Check out Ricky's report to find out more about mummies and where else in the world they've been found...
A large number of works of art have been seized from a Cotswold art gallery after allegations of fraud and theft.
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Two ancient mummies more than a thousand years old have been found in Peru in South America.