MADRID — Whether by law or intimidation, Spain has become a country where the risks of free expression have quietly mounted in recent years.

Puppeteers have been prosecuted for inciting terrorism. So have a 21-year-old Twitter user, a poet and some musicians, including the 12 members of a band. A much criticized law has made it illegal to film the faces of police officers on the streets, and sharply restricts public gatherings.

On Wednesday, the chill entered the realm of contemporary art, when Madrid’s main exhibition center ordered that a work labeling Catalonia’s separatist leaders as political prisoners be removed from an international arts fair.

The exhibition center, known as Ifema, is controlled by the regional and local governments of Madrid, though it remains unclear who exactly decided to order the removal of the work, “Contemporary Spanish Political Prisoners,” by the artist Santiago Sierra.