Police made three arrests in Hassocks over the weekend after officers had to break up a 'large private birthday party'.
Officers were called to an address in Hurst Road, Hassocks, at 8pm on Saturday night (September 21), after reports that hundreds of youngsters, roughly equal proportions of boys and girls, were making towards it from the nearby railway station.
Police said a large number of officers had to force out about 800 15 to 16-year-olds from both the party and the surrounding neighbourhood, over a period of nearly four hours.
Many were intoxicated and were openly using drugs, said a Sussex Police spokesman.
Three arrests were made for breaches of the peace, confirmed the spokesman, who added that officers will be working with partner agencies to deal with those who were arrested with a view to implementing plans to help them react more responsibly in the community. Further police enquiries are also being made to trace others who attended.
The spokesman said: "The majority of those involved did not come from the local area, and some are known to have come from the Lewes and Hailsham areas and with the assistance of colleagues in British Transport Police we were able to move most of them away from the locality.
"A Section 35 Dispersal Order was put in place to give officers further powers to disperse people. Such Orders cover specific areas and allow officers to remove people by force if necessary. A failure to comply with an Order can result in an arrest.
"There was one report of criminal damage to a parked car but fortunately no injuries were reported."
Sergeant Allan Philip added: "It is disappointing to note the age of those involved and the level of intoxication. Most of the alcohol will have come from somewhere prior to most arriving in Hassocks and our enquiries may result in other individuals being dealt with for buying alcohol for peoples under 18 years of age.
"A clear message needs to go out to the parents and guardians of those involved, that the police are not your child minders and that where possible you should consider where your children are, who they are with and what they are doing.
"If anyone has any information about the background to this incident please contact Sussex Police online at https://www.sussex.police.uk/contact/af/contact-us/ or call 101, quoting serial 1271 of 21/09."