South Africa's public broadcaster SABC has launched an inquiry after its evening news bulletin showed the beheading of a US hostage in Iraq.
SABC showed the moment of Mr Armstrong's death
SABC's Xhosa language programme broadcast graphic footage of a militant cutting off the head of engineer Eugene Armstrong with a knife.
Corporation spokesman Paul Setsetse said a programme producer had been suspended pending the investigation.
Mr Setsetse apologised for what he said had been a "terrible mistake".
The news programme showed part of the video, which had been posted on the internet by the hostage-takers, in its 1930 bulletin.
"Everybody was shocked by the viewing," Donna Mohamed of the Broadcasting Complaints Commission of South Africa (BCC) told AFP news agency.
"It went out so early. It's family time and most parents encourage their children to watch the news and see what's happening."
The BCC said it will watch the footage and decide what action to take against SABC.
Ms Mohamed said the same pictures were shown on the privately-owned eTV network, which also faced possible action.
However, this was denied by eTV editor-in-chief Joe Thloloe.
"We in fact cut the visuals before the beheading, although we continued with the screams of the victim. It was not prolonged, not graphic - the fade-off constituted sensitive editing," he told the Sapa news agency.
SABC apologised to viewers during the news programme for having broadcast the footage.
"We regret the incident," Mr Setsetse told AFP. "We apologise to the public, to our viewers. It was a terrible mistake by the person responsible and we have taken action against that person," he said.