A fake painting that sold for £8.4 million signals a highly skilled forger in the arts market

A painting sold by auction house Sotheby's for £8.4 million ($10.6 million) has been assessed as fake, raising fears that more multimillion pound forgeries might be on the market, according to a report in the Financial Times.

The work, by Dutch artist Frans Hals, was sold to an anonymous US buyer in 2011.

However, it was taken back by Sotheby's after its buyer discovered its connection to another fake painting, according to the Daily Mail. The auction house then used pigmentation tests to determine that the work is indeed a fake.

The scandal goes back to earlier this year. It started when a painting by German painter Lucas Cranach was seized by the French authorities at an exhibition in the south of France.

That painting called 'Venus', dated from 1531. It sold in London for £6 million, but is now under assessment at the Louvre, and is believed to be fake.

When the buyer of the £8.4 million Hals painting discovered that his painting had been supplied by the same art dealer - Mark Weiss - as the French fake, he sent it back to Sotheby's, whose experts reassessed it and decided it was a forgery.

In an interview with the Daily Mail, art dealer Bob Haboldt described the episode as "the biggest art scandal in a century."

He described the person behind the fakes as the 'Moriarty of the Old Master', in a reference to the mastermind villain in the Sherlock Holmes books. An Old Master is any painter from Europe who painted before 1800.

There are now concerns that the market has up to 25 other fakes in it. The Daily Mail reports that the scandal could cost art investors £200 million.

It also says that Sotheby's are threatening legal action against Weiss to recover the cost of refunding the Hals painting.