An actor portraying a suicide bid in an Austrian play accidentally slashed his own throat on-stage following a prop mix-up.

Daniel Hoevels, 30, collapsed with blood pouring from his neck after using a real blade instead of the blunt stage knife.

He was taken to the hospital after the dramatic scene at Vienna's Burgtheater.

The audience had been raptured, unaware the actor was facing his own demise for real.

But when he failed to greet their applause for the show's spectacular special effects with a bow they separated fact from fiction.

Police are now investigating whether the mix-up was murderous.

Officers have refused to rule out the possibility that a jealous rival may have switched the blades.

The knife had been bought at a local store and police are asking if props staff forgot to blunt the blade for the performance of Friedrich Schiller's play Mary Stuart, about Mary Queen of Scots.

"The knife even still had the price tag on it," said a police investigator.

The theater's props manager has been quizzed by police about the weapon, Austrian daily Osterreich reported.

The actor recovered after emergency treatment and even appeared on stage the next night with a bandage around his neck.

"If Hoevels had hit an artery or cut only slightly deeper, he would have died on stage," a doctor said.

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