The cameraman was getting pictures for the Hillside Animal Sanctuary at Frettenham, Norfolk, which has been investigating factory-farming practices for 11 years.

'Horrified by film'

Bernard Matthews said it would take whatever steps were necessary to ensure such maltreatment never happened again.

Technical director Jeremy Hall read a statement saying the company had been horrified by the video.

"We are horrified by the contents of this filming, and condemn unreservedly such cruelty," he said.

"The people involved have already been suspended, pending a thorough investigation that is likely to result in prosecutions and dismissals.

"In this business we are committed to the highest standards of animal welfare.

"We recognise that our systems have failed in this instance, and we are carrying out an immediate and thorough review. We will take whatever steps are necessary to ensure such maltreatment does not happen again."

On Monday, the RSPCA said it was studying the pictures before deciding whether to prosecute.