The man entered the inquiry at the High Court in London from behind the stand where Blair and the judge were seated, and shouted: "This man should be arrested for war crimes. The man is a war criminal."

Court officials bundled him out of the room after about 20 seconds and inquiry chairman Lord Leveson called for an immediate inquiry into how he had been able to disrupt the proceedings.

It was the second time in less than a year that a protester has been able to break into a hearing involving links between British politicians and the media.

In July, a spectator was able to approach media mogul Rupert Murdoch as he gave evidence to a parliamentary committee and threw a foam pie at him.

Blair testified that he decided to court the media rather than risk the wrath of powerful media tycoons while prime minister.

Blair's relationship with the press, and with Rupert Murdoch in particular, came under scrutiny at the inquiry, which has broadened to include an examination of the close ties between politicians, the press and the police.

Blair said the close relationship between politicians and the media was inevitable but that it became unhealthy when media groups tried to use their newspapers as instruments of political power.