Samsung has deactivated some 26,000 mobile phones stolen from a Middlesex freight forwarding warehouse on Sunday evening.
Originally worth around £4.2m, the high spec A300 handsets are silver with Orange or One2One logos, but cannot now be used in the UK. "They are now worthless," said Detective Inspector Morgan O'Grady.
The Home Office last month called on mobile phone companies to do more to block the use of stolen phones, but the operators said that, even if calls were blocked, stolen handsets could still be used overseas.
Samsung has offered a £200,000 reward for information on the theft. Police said there was no sign of forced entry at the warehouse.
Detectives believe the thieves used an articulated lorry to transport the phones, which were stacked on around 60 pallets. They were imported last week and were waiting to be delivered to shops.
Last July, eight men were charged with stealing £3m worth of Nokia 8850 and 8210 mobile phones from a Heathrow Airport warehouse.
Surrey police believed they had cracked an organised crime ring which has staged a number of heists in the south east and Thames Valley areas, although previous thefts have involved no more than £500,000 worth of phones.
Cotton seedling freezes to death as Chang'e-4 shuts down for the Moon's 14-day lunar night
Fortnite easily out-earns PUBG, Assassin's Creed Odyssey and Red Dead Redemption 2 in 2018
Meteor showers as a service will be visible for about 100 kilometres in all directions
Saturn's rings only formed in the past 100 million years, suggests analysis of Cassini space probe data
New findings contradict conventional belief that Saturn's rings were formed along with the planet about 4.5 billion years ago