Heroin worth more than £8.5 million has been found stashed in the side of boxes of fruit and nuts at Heathrow Airport.
Border Force officers found 170kg of the class A drug hidden in envelopes that were concealed in the walls of a consignment of 630 boxes on May 21.
Two men, aged 36 and 51, were arrested near Bradford on suspicion of importing class A drugs the following day, and a third was held in Birmingham on May 23.
They have all been released under investigation.
Minister for Immigration Compliance and the Court Chris Philp said: “This substantial seizure was the largest class A drugs detection so far this year by Border Force at Heathrow.
“Illegal drugs fuel crime, violence and exploitation which is why our work to prevent them reaching our communities is so vital.”