British graffiti artist Banksy is drawing crowds to his New York City mural but for an unfortunate reason.

Somebody has added a signature tag to his artful protest over the imprisonment of a Turkish artist and journalist.

Plenty of pedestrians were taking a look at the graffiti, which is scrawled in red across the bottom half of his 70ft-long mural.

The mural bearing the slogan Free Zehra Dogan was recently installed on the Houston Bowery Wall, made famous by Keith Haring in the 1970s.

The mural before it was vandalised (Mary Altaffer/AP)
The mural before it was vandalised (Mary Altaffer/AP)

The mural protests against the jailing of Dogan, an ethnic Kurd, after she painted the Turkish flag flying over the rubble of a destroyed town.

Dogan was convicted last March.

Banksy’s mural shows her jailed behind a set of black tally marks representing her days in prison.