More than 2,000 litres of illegal booze was seized in the biggest ever haul by customs officers and police.
The seizure was made on Tuesday from four independent stores in Wealdstone in raids by HM Revenue and Customs (HMRC), in collaboration with Harrow police and Harrow Borough Council.
Officers confiscated 1,704 litres of beer, 272 litre of wine, 56.7 litres of spirits, half a kilo of chewing tobacco, 120 cigarettes worth around £5,000 in lost tax duty revenue.
HMRC spokesman Jennie Kendall said: "This illegal trade has a devastating impact on legitimate retailers, who have to compete with black market traders.
“It’s robbing the UK economy of vital funding and those selling these goods do not promote they are buying them from criminals - the profits of which are funding organised crime to the detriment of all our communities.
“We will continue to also work with trading standards and police law enforcement colleagues and seek to prosecute those involved in this form of criminal activity where appropriate.”
The haul was so huge officers had to call in a lorry to collect all the illegal produce and Wealdstone High Street was temporary closed as the crates were loaded.
Harrow Council leader Councillor Susan Hall said: "The vast majority of honest local traders would have found their prices and margins undermined had this large haul of illegally imported alcohol not been found.
“We want to support businesses, and making sure they are on a level playing field by removing unfair competition vital in achieving this.
She added: “Such a large haul shows the value of these Days of Action, and how by working together with our partners we can make a real difference.
“We tend to focus on known concerns or problems in certain areas, so it's particularly pleasing to see such a positive outcome on this occasion."
Dave Corby, environmental services manager at Harrow Council said: “Selling alcohol and cigarettes without paying duty is blatantly flouting the rules and it is not fair on other businesses that are doing everything legitimately.
“We will continue to crack down on this type of activity and the result from the joint operation today showed that businesses cannot just get away with it.”