Berlin -- Authorities in Berlin said an exhibition of work by the Danish art group Surrend would re-open Tuesday despite a reported threat of violent protests by Muslims.

One of the 21 posters by the satirical artists depicts Islam's holiest place, the cube-like Kaaba in Mecca, with the words "Stupid Stone" written above it.

A poster showing a man in Jewish headgear marked "Stupid Hat" appeared in the street outside the gallery on Monday, but it was not certain if the same artists or someone else had drawn it.

Municipal authorities said Monday they had hired two private security guards to stand in the gallery. A senior official said earlier a police patrol would also drive by hourly.

The Kunstverein Tiergarten art gallery complained it was not being provided with sufficient police protection. It said the art show was "in no way whatever anti-Muslim."

It said last week protesters had threatened to use violence if the satirical posters were not withdrawn. The exhibition was opened on February 22.

Surrend, which was formed in 2006, has designed a series of posters poking fun at world leaders.

In December 2006, it placed an advertisement in a small Tehran newspaper insulting Iranian President Mahmoud Ahmadinejad with a hidden message spelling out the word "swine."

DPA with Expatica