A man has claimed responsibility for defacing a valuable Mark Rothko at the Tate Modern art gallery, but denied he is a vandal.
Scotland Yard has launched an investigation after a man was seen daubing black paint on the mural piece on Sunday afternoon.
The writing on the bottom-right corner of the piece appears to read: "Vladimir Umanets, A Potential Piece of Yellowism."
Mr Umanets, who is originally from Russia, said he had written on the painting, but insisted his aim was not to destroy or deface it.
"Some people think I'm crazy or a vandal, but my intention was not to destroy or decrease the value, or to go crazy. I am not a vandal," he said.
Mr Umanets, who studied art, is one of the founders of "Yellowism", which he describes as "neither art, nor anti-art. Yellowism is not art, and Yellowish isn't anti-art. It's an element of contemporary visual culture. It's not an artistic movement. It's not art, it's not reality, it's just Yellowism. It can't be presented in a gallery of art, it can be presented only in a Yellowistic chambers.
"The main difference between Yellowism and art is that in art you have got freedom of interpretation, in Yellowism you don't have freedom of interpretation, everything is about Yellowism, that's it. I am a Yellowist. I believe what I am doing and I want people to start talking about this. It was like a platform.
"I don't need to be famous, I don't want money, I don't want fame, I'm not seeking attention. Maybe I would like to point people's attention on what it's all about, what is Yellowism, what is art?"
Mr Umanets, who would not reveal his age or where he lives, said he knows he is likely to be arrested, but added: "I believe that from everything bad there's always a good outcome so I'm prepared for that but obviously I don't want to spend a few months, even a few weeks, in jail. But I do strongly believe in what I am doing, I have dedicated my life to this."
The Tate Modern was shut for a short period on Sunday and then reopened after the incident. The 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.