(news.bbc.co.uk) - Airport-style scanners will be used to search people attending a production of a Mozart opera in Berlin featuring the severed head of the Prophet Muhammad.
Security has been tightened because of fears of a Muslim backlash against Deutsche Oper's version of Idomeneo.
Jesus, Buddha and Greek god Poseidon are also decapitated in the show.
But Islamic tradition bans images of Muhammad, and there were violent protests around the world when a Danish newspaper printed 12 cartoons of him.
The production, by director Hans Neuenfels, received its premiere three years ago, and it was his idea to include the controversial twist with the religious icons.
It gained little attention at the time, but the subsequent riots over the Danish depictions meant that Monday's performance has generated controversy.
In September, Berlin's opera house scrapped the show on police advice. But this decision received a mixed response in the German capital.
While some Muslim leaders praised the move, Kenan Kolat, who leads the country's Turkish community, branded it as a step back to "the Middle Ages".
Chancellor Angela Merkel and Interior Minister Wolfgang Schaeuble were also unhappy about the cancellation.
And Mr Neuenfels himself was critical of the revival of his production, insisting his staging was not altered.
The scene in question, where the king of Crete presents the severed heads, was a protest against "any form of organised religion, or its founders", he added.
Police spokesman Berhard Schodrowski told the Associated Press that officers would be positioned around the venue and were "ready for any eventuality".