Police are appealing to parents to stop their children from attending an "End of Year Party" on Wimbledon Common tomorrow night.
A month after a 15-year-old died after attending an illegal rave in Croydon, police are concerned for the safety of almost 2,000 young people signed up on social media to descend on the common after 7pm.
Detective Chief Superintendent Stuart Macleod, Merton borough commander, warned parents the event is likely to be a magnet for violent criminals and drug dealers.
He said: "Whilst I am in no doubt that most of those attending will be intent of having a good time, when young people gather in large groups like this, they often seem to drink too much and this makes them particularly vulnerable.
"On previous occasions when these gatherings have been widely advertised, they have been targeted by offenders from other boroughs who see them as an opportunity to commit crime, and there have been incidences of assault and robbery.
"People have also been hospitalised as a result of consuming too much alcohol, taking controlled drugs, or a combination of both, and the recent death of a young person following a 'rave' in Croydon a few weeks ago highlights the very real risks associated with these types of events."
"Wimbledon Common is part of the borough-wide ‘Controlled Drinking Zone’ and police officers will utilise their powers under this legislation to seize alcohol if the situation warrants it at the time."
So far more than 1,900 school pupils have said they are going to the event on social media site Pinvents.
An illegal rave planned on Pinvents for Wandsworth Common on Saturday, June 21, was cancelled after police sealed off low-security buildings and warned people not to attend.