Extra police are being drafted into the Windsor area after three nights of violent clashes between white and Asian youths
Gangs have fought battles in the streets using baseball bats and pitchforks. A Muslim-run dairy which wants to build a mosque was petrol bombed.
Dozens of officers have been deployed to stop and search youths and mounted police are being brought in.
The Queen usually spends weekends at Windsor Castle and no decision has yet been taken over whether she would change her plans. A senior source said: "We are aware of what is happening and all appropriate security measures are in place."
Tensions have been growing between residents and the owners of the dairy, who have applied to convert an office building into a mosque for their workers.
Despite a lack of planning permission to use Technor House as a place of worship, workers and visitors have been praying there.
Violence flared for the first time on Monday outside the building in Vale Road in the Dedworth area of Windsor.
There was an altercation between a teenage boy and dairy staff during prayers. It escalated and the windows of several vehicles were smashed.
Amid claims that the boy, his mother and teenage sister were assaulted, up to 50 young people clashed on Tuesday night.
Windows of the makeshift mosque and dairy vehicles were smashed. Residents said gangs of Asian youths travelled from Slough to fight the white gang. One youth was reportedly arrested for carrying a 12-inch knife.
Muslim dairy attacked by gang