Police raided four homes today in the latest stage of a four-week crackdown ahead of this year's Notting Hill Carnival.
Officers fear crime gangs linked to drugs and violence could clash during the August Bank Holiday weekend extravaganza.
They have linked up with forces across the country, including the West Midlands and Manchester, to gather information on suspects.
Intelligence officials have been monitoring Facebook and Twitter where many thugs exchange threats in the run-up to the carnival.
Police have arrested 69 suspects on suspicion of conspiracy to supply drugs, possession of stolen property and possessing weapons.
They have seized £60,000 cash, large quantities of crack cocaine, cocaine and cannabis, and weapons including a samurai sword, hunting knives and a martial arts throwing star.
Chief Inspector Chris Allmey, who is responsible for the operation, said police want to stop potential troublemakers from going to the carnival.
He said: "Gang members who go to the carnival are spoiling it for everyone else. We are looking to stop these people attending to make it safe for everybody who wants to go.
"Notting Hill has a worldwide reputation and people come from all over to see it. We want to stop troublemakers from attending in the first place.
"The difference this year is we are doing it for four weeks, not two, and we could have done it for another two weeks on top.
"It has to have a punchy effect right before carnival to make sure the people we are dealing with get the message, 'Do not go to carnival'."
In today's move, codenamed Giants, teams of officers from the Met's territorial support group searched four homes linked to two drug dealers.
Wearing protective clothing and helmets, they searched homes in Hillman Drive, Shrewsbury Street and a sixth floor flat at the Peabody Estate in north Kensington, west London.
A fourth team of officers raided a flat in Redwood Court, Fulham. Officers were planning to execute a further six search warrants later today.
At the Hillman Drive home, a woman shouted her grandchildren were asleep as officers smashed open the front door. Nothing was found and no arrests were made.
In nearby Shrewsbury Street a man and women were questioned as officers removed some items, believed to include personal possessions, mobile phones and documents.
One neighbour said the modern three-storey terrace is a well-known drug den where men sell crack cocaine, and is regularly raided by police.
She said: "It's the same every year. They come here and nothing changes. Everyone knows what is going on in this street. There are people coming and going at all times."
Police said the properties were linked two two drug dealers who use some to stash drugs including crack cocaine and heroin and others as a base to sell them.
One dealer has been watched using a convenience store near his home to sell drugs but moved to other premises when it went out of business.
Officers believe the suspects may also have access to guns and could use family members or close associates to conceal them as they are often targeted by police.
A massive £6 million policing operation will swing into gear during the holiday weekend to protect up to a million carnival visitors.
All entrances will have search points in a bid to prevent weapons being carried on to the streets while specialist spotters watch out for known criminals.
Teams of officers will target pickpockets who have blighted previous carnivals and dog owners have been told to leave animals at home.
Last year more than 200 people were arrested as a bulletproof vest and a knife were recovered from members of one group who gathered at Victoria station.