Protesters planning to disrupt the Labour Party conference in Brighton are being urged to stay away by police.
The Brighton Centre is hosting the Labour Party conference
Up to 20,000 people are expected to attend the event at the Brighton Centre between 26 and 30 September.
Sussex Police Chief Constable Ken Jones said he did not want his officers diverted away from their core task of preventing the threat of terrorism.
He also asked for "full co-operation" from legitimate protesters to make sure the event passed off safely.
The chief constable said: "In the last few days we have seen a number of dangerous stunts and disorderly demonstrations in London, which have irresponsibly diverted police officers from important tasks related to national security.
"I ask those intent on publicity stunts, civil disobedience or worse, to stay away from Brighton and Hove and let my officers concentrate on the real threats we currently face.
"Those who indulge in apparently harmless stunts and disorderly demonstrations need to know that such activities have the potential to divert and weaken our defences and are against the law."
Mr Jones said lawful protests at the event would be facilitated, but groups and individuals should inform officers of their plans.