Cate BlanchettCate Blanchett has suffered a head injury during a theatre performance.

The 40-year-old was accidentally struck by a radio during a fight scene with her co-star, Joel Edgerton.

Thankfully, the injury is only minor.

"There was a minor incident on stage that unfortunately did injure Cate," said Tim McKeough, a spokesman for The Sydney Theatre Company, where she is starring in A Streetcar Named Desire.

Mr McKeough said she was "absolutely fine."

The brave actress continued acting for around a minute, before leaving the stage with blood pouring down her head.

Wednesday's show was subsequently cancelled, but Mr McKeough said Cate was confident she would be back on stage by Thursday.

An audience member told Macquarie Radio network: "She had blood streaming down the back of her head and blood on the back of her neck."

Mr McKeough denied reports the radio prop had been thrown at her.

"That is not correct. There is no point in the show in which the radio is thrown at her.

"There was a moment when another actor lifted the prop above his head and she somehow sustained a minor blow to the head."