A Russian man has claimed responsibility for scrawling graffiti on a mural by modern American master Mark Rothko at London's Tate Modern.

The mural, one of Rothko's Seagram series, was defaced Sunday with what appears to be the words "Vladimir" and "a potential piece of yellowism."

Scotland Yard says it has launched an investigation.

Vladimir Umanets, who identifies himself as one of the founders of "Yellowism," says he is behind the graffiti but denies being a vandal or fame-seeker.

He told Britain's Press Association on Monday that he wants to draw people's attention to "Yellowism," which he describes as "an element of contemporary visual culture."

Umanets told the news agency he expects to be arrested but believes his scrawl increased the painting's value.