A naked male protester was arrested outside the Brighton Centre as delegates arrived for the final session.
The man appeared in front of the railings where delegates and media were queuing to gain entry to the centre.
He held up a newspaper headline saying "Stop This War".
The protester was immediately wrestled to the ground by police officers who found a blanket to cover him up. He was taken for questioning.
Stuart Holmes, who has been carrying out a one-man anti-smoking protest for four days outside the conference, said: "He just appeared from nowhere. There was a shout from a police officer and they wrestled him to the ground."
A spokeswoman for Brighton police said: "A 31-year-old man was arrested outside the conference centre and is being questioned about an indecent exposure offence."
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