Police issued a dispersal order after a standoff at a barracks earmarked for 600 asylum seekers.
Officers were responding to reports a man was assaulted as protestors blocked the main entrance to the camp.
A spokesman for Sussex Police said they were called to Crowborough army camp on Tuesday (December 9) night after reports a crowd were refusing to let workers leave.
Police are investigating reports one person was assaulted and threatened during the confrontation involving people monitoring the camp.
The Section 34 Dispersal Order for all entrances to the camp will stay in place until Wednesday evening.
A large crowd gathered at the main entrance on Tuesday night.
Several police cars arrived on the scene, with officers from all over Sussex called to the camp near Ashdown Forest.
A spokesman for the force said: "We responded to reports of a number of people blocking the entrance to the army training camp in Crowborough and preventing workers at the site from leaving on Tuesday night.
"We are investigating a report that one person was assaulted and threatened with violence.
"We have issued a Section 34 Dispersal Order for the A26 Uckfield Road junction with Chillies Lane, including Chillies Lane, the A26 north into Beacon Road junction with Church Road, Uckfield Road junction with Sheep Plain and Sweethaws Lane, Warren Road and all access roads to the camp itself, which runs from 9.15pm on Tuesday to 9.15pm on Wednesday."
The order gives police temporary powers to prevent people gathering or requiring them to leave the area or face arrest.
"We will take robust action against anyone involved in criminality and anti social behaviour," Sussex Police said.
