Residents in the St Giles High Street area of central London say there has been an influx of drug dealers and addicts into the area.
They say the influx follows a police operation in neighbouring Soho to clean up the area ahead of the Olympics.
Labour councillor for Holborn Sue Vincent said: "It's been pushed out of Soho during the Olympic period and as a consequence has come here."
Scotland Yard said it aimed to make the West End a safer and more secure place.
Operation Trafalgar started on 29 March with extra officers deployed in Westminster to reduce robberies, violence, sex crimes and vehicle crime.
Since the start of the operation, more than 1,700 people have been arrested, with 620 people having been charged with 691 recordable offences.
Of these, 141 people have been charged with a total of 171 drug offences.
But some people living and working around St Giles area close to Tottenham Court Road, in the borough of Camden, said they had witnessed a rising number of assaults and robberies.
Mark Webster, a manager at 12 Bar, on Denmark Street, just off St Giles High Street, said: "On bad nights you could have 50 or 60 people in the immediate vicinity looking for trouble.
Ms Vincent said: "We're having to walk through gangs of 20 to 25 people who are dealing drugs, acting in an incredibly chaotic manner and are incredibly threatening."
A Westminster police spokesman at Scotland Yard said: "Operation Trafalgar is a long-term approach to make the West End a safer, more secure and enjoyable place.
"Part of the work of Operation Trafalgar is to identify and tackle class A drug dealers and users and take swift and robust action.
"As a result there is a positive charge policy for possession of class A drugs throughout the borough.
"We also continue to work alongside our colleagues in Camden and with other partners to tackle crime and anti-social behaviour."