Daniel Hoevels (standing) and Renato Schuch perform during a dress rehearsal for William Shakespeare's Much Ado About Nothing in August 2006 in Salzburg. (JOSCH/AFP/Getty Images)

An actor at Vienna's Burgtheatre slashed his throat open on stage after the blunt stage-prop knife he thought he was using turned out to be a real knife.

Daniel Hoevels, 30, was supposed to kill himself in the final scene of Friedrich Schiller's play Mary Stuart, about Mary Queen of Scots. He played Mortimer in the production by the Thalia Theatre company from Hamburg.

But the dramatic scene turned into a real-life drama as he staggered off-stage with blood pouring from his neck.

The audience members are reported to have applauded what they thought was a stunning performance, until they realized something was wrong.

Hoevels was rushed to hospital where doctors said he had narrowly missed cutting a main artery.

"If the actor had put a little more pressure on the knife or even struck an artery, he would probably have bled to death on the stage," a doctor told the Oesterreich newspaper.

Austrian police are investigating how a real knife was substituted for a prop knife. They have not ruled out foul play.

After emergency treatment following the Saturday incident, Hoevels declared that the show must go on. He returned to the stage on Sunday night with a bandage around his neck to again play the suicide scene.