Police are hunting for a vandal who walked into the Tate Modern art gallery and defaced a valuable painting by Mark Rothko.
The visitor daubed black paint on the mural piece during a visit to the popular landmark yesterday afternoon, a spokeswoman for the gallery said.
The art gallery said it does not have a price for the defaced piece, but paintings by the Russian-born artist often fetch tens of millions of pounds.
Earlier this year, Rothko's Orange, red, yellow was sold for £53.8 million - the highest price ever paid for a piece of post-war art at auction in New York.
Scotland Yard confirmed it had launched an investigation into the matter and is yet to make any arrests.
The force said it was looking for a white male in his late 20s.
More top news
Sir John Vickers proposed reforms to make the financial system safer. Now he has accused the Bank of England of "going easy" on the banks.
Widespread frost expected overnight as temperatures drop below freezing ahead of a chilly start to the week.
Obese people make a mountain out a molehill - because they see distances as further and hills as steeper than slim people, say scientists.