Family of Mark Rothko speak out over act of vandalism at Tate Modern, adding they were warmed by the response from the British public

The family of Mark Rothko have spoken out over the act of vandalism carried out on one of the Tate Modern’s prized examples of the artist’s work, but said they were “heartened” by the response from the British public.

One of the abstract expressionist painter’s Seagram murals on display in the London gallery, Black on Maroon, was vandalised yesterday afternoon.

According to eyewitnesses a man in his 20s calmly stood in front of the painting before walking up and writing a motto in the corner before walking out.

The daub read “Vladimir Umanets. A potential piece of Yellowism”. The man, in his 20s said he was not a vandal and said he was influenced work to dadaist artist Marcel Duchamp.

Rothko’s children Kate Rothko Prizel and Christopher Rothko released a statement saying the family was “greatly troubled by yesterday’s occurrence but has full confidence that the Tate Gallery will do all in its power to remedy the situation”.

They said their father had been impressed “by the warm embrace” his work had received from the British public. “We are heartened to have felt that embrace again in the outpouring of distress and support that we and our father have received both directly and in public forums,” they added.

The police are pursuing several lines of enquiry and as yet no arrests have been made, although someone purporting to be Umanets acknowledged he was likely to be arrested soon.

Bonnie Clearwater, chief curator of the Museum of Contemporary Art in Miami and a Rothko expert said: “I couldn’t believe it when I heard the news.”

She said the fascination with his work was “the paintings hold the viewer frozen. He created a sense of movement, expanding and contracting in the viewer’s eye.”

Rothko, who died in 1970, had been commissioned to provide the paintings for the Four Seasons restaurants at the Seagram Building in New York in 1959. Yet he pulled out of the deal and some years later presented the Tate with nine of the paintings intended for the restaurant.

The artist donated the works, dubbed the Seagram paintings to the museum in 1969, “sensing the commitment of the institution to his work and impressed by the warm embrace it had received from the British public,” the children said.

His work remains hugely desireable. Orange, red, yellow sold for $86.9m at Christie’s in New York earlier this year, the most ever paid for post war art.

The room which held the Rothko paintings was closed today, while the damaged work was taken away for conservation.

The initial inspection led the Tate’s experts to believe that black paint was used rather than marker pen, because of the drips down the canvas but there was still no confirmation by the end of the day.

A spokeswoman for the Tate said: “The painting is our priority, our conservators are amazing. They have done a lot of work on the Rothkos over the years.”

The Tate declined to comment on whether it would beef up its security measures following the incident, just saying that there is “always tight security” at the gallery and adding “there has to be an element of trust”.