The pieces from Rothko's Black and Maroon series, like many of his popular and valuable works from the 1950s and 1960s, consist solely of colored stripes. London's Tate Modern museum has hung them vertically, but evidence from the artist -- who committed suicide in 1970 -- suggest they should be hung horizontally, the Sunday Times of London reported.

Rothko's signature on the back of the paintings is thought to reflect his wish they be hung horizontally, an article in The Art Newspaper, a British arts journal, reported.

"Rothko was always prevaricating over how his art should be shown," said Waldemar Januszczak, art critic for the Sunday Times. "To me, the hang of these two paintings in the current exhibition seems right. But if it is clear that Rothko himself wanted them to be horizontal, you would be crazy to go against his wishes."

A Tate Modern spokesman told the newspaper: "We believe it's more appropriate for these two paintings to be hung vertically."