Rupert Murdoch has been pelted with a white substance during his appearance before MPs.
Mr Murdoch's wife Wendi and his son James jumped to his defence as the attack was launched as the final questions were being asked by MPs.
The hearing was suspended as a man wearing a checked shirt with what appeared to be foam splashed across his face was detained by police.
Mr Murdoch, 80, was apparently pelted with a plate of foam.
James Murdoch was in mid-sentence as the attacked was launched.
Wendi Murdoch, who had sat behind her husband throughout his appearance before the Commons Culture, Media and Sport Committee, appeared to strike back at the assailant in defence of her husband.
The hearing resumed 10 minutes after the attack with Mr Murdoch now wearing shirt sleeves but apparently unharmed.
Eyewitnesses said a member of the audience sat at the back of the room stood up and walked around to the front where Mr Murdoch was giving evidence and threw what appeared to be a paper plate covered in shaving foam at him.
As the protester was being taken from the room, Mr Murdoch's wife threw the empty paper plate at him. The session was then suspended.
As the man was being led away in handcuffs escorted by a single police officer, he refused to give his name, saying: "As Mr Murdoch himself said, I'm afraid I cannot comment on an ongoing police investigation." His shirt and hair was covered in what appeared to be white shaving foam.