Police have arrested at least 26 people in a series of dawn raids ahead of Notting Hill Carnival.
Eight addresses in Lewisham, south-east London, were searched and eight arrests made early on Tuesday morning in a planned, intelligence-led operation.
A number of raids were also carried out in Kensington and Chelsea, the borough where the world-famous carnival takes place every August bank holiday weekend.
Officers searched 21 homes in Kensington and Chelsea, Hammersmith and Fulham, Westminster, and Wandsworth, arresting 18 people.
The crackdown - against knife crime, drugs and child exploitation - was carried out by more than 100 officers from the Metropolitan Police, City of London Police and the British Transport Police.
Since Friday August 11, and not including Tuesday’s raids, officers have made more than 290 arrests for a range of offences, recovering 190 knives and 18 firearms.
Tuesday’s arrests were predominantly for possession with intent to supply drugs.
If some of those arrested are then bailed, they will be forbidden from attending the carnival, Scotland Yard said.
Officers known as "super recognisers" will be in the area and monitoring CCTV to help spot those banned from the parade.
Chief Superintendent Robyn Williams, the Met's spokesman for Notting Hill Carnival, said: "Our officers have been proactive and focused on tackling serious violence and knife crime across London.
"Today's operation is aimed at ensuring that those who intend to cause trouble at Carnival are prohibited from doing so.
"We are committed to ensuring that Carnival remains a safe, vibrant and enjoyable event; troublemakers are not welcome.
"We will be uncompromising in our operations to keep our communities safe and secure. People can expect to see operational activity right up until, and throughout the bank holiday weekend."
A further three men and two women were arrested at a terraced house in south-east London, while a young child was taken by police to stay with her grandparents.
In the property, uncut crack cocaine with an estimated street value of £60,000 was discovered, along with multiple bags of powder thought to be heroin.