Fifty-three people were arrested in Brighton yesterday during a protest but all of them have been released without charge.
Sussex Police said that most of the arrests during the Smash EDO demonstration were made to prevent a breach of the peace.
The force estimates that the bill for policing the protests will be more than £100,000 although it does not yet have a final figure.
The protesters were trying to target the EDO MBM Technology factory in Home Farm Road, Moulsecoomb.
About 200 people took part in the protest – called Hammertime by the organisers.
And about 250 police officers were deployed, some from other areas.
Chief Superintendent Graham Bartlett, the Brighton and Hove district commander and the officer in charge of policing the demo, said: “There were more arrests this time than in previous years to prevent additional disruption to the community.
“The public rely on us to reduce disruption to their lawful activities and to prevent serious offences so that is what we did.
“The majority of arrests were to prevent a breach of the peace and all of these people were released without charge when the risk of a breach of the peace had been averted.”
Sussex Police said that, in addition to the arrests made for breach of the peace, officers also detained ten other people.
A man, 28, and a woman, 22, were arrested mid-afternoon on suspicion of criminal damage after an attempt to glue themselves to the RBS bank in the town centre. They have been bailed for further inquiries.
Two men, aged 18 and 39, were arrested for affray near Brighton Station later in the afternoon and have been bailed.
A man, 31, and a woman, 48, were arrested for stealing a bicycle, and the woman for having drugs. Both were bailed.
A man, 22, was arrested for the theft of a mobile phone SIM card.
A man, 25, and woman, 20, were cautioned for having cannabis.
A 42-year-old man arrested for having a knife as he made his way to the protest meeting point. He faces no further action.
