Westminster's resident anti-war protester Brian Haw has been arrested for alleged breach of the peace.
Mr Haw was released without charge
The 56-year-old from Worcestershire said he was forced to briefly leave his camp in Parliament Square where he has held a four-year vigil.
He was taken to Charing Cross police station and released without charge shortly afterwards.
Mr Haw recently won a High Court battle to continue his one-man protest despite new laws coming into force.
Mr Haw claims he was arrested after police officers quizzed a woman who was guarding his banner-clad site while he slept.
"They told her she was demonstrating and it was against the law, but she said she was just a friend of mine," said Mr Haw.
"I stuck my head out of my sleeping bag and said: 'Are you bothering this lady?' and, eventually, they arrested me for breach of the peace.
"I'm not breaching the peace. I'm fighting for it."
It was the first time he has been arrested since a High Court ruling in July recognised his right to continue his one-man protest.
New legislation requires protesters to obtain permission from police before mounting a demonstration within a mile of parliament.
A Met Police spokesman confirmed a 56-year-old man was arrested at 0905 GMT at Parliament Square for breach of the peace and was later released without charge.