Officers have seized 25 inflatable boats at East Midlands Airport which the National Crime Agency says were destined for Channel people smugglers and could have carried around 1,700 people.
The NCA announced the operation on 6 October. The boats were discovered in pallets within an air-freight shipment travelling from Turkey to the Netherlands.
The NCA and Home Office Intelligence Team identified the consignment. When it passed through the airport's freight hub on Friday 2 October, NCA and Border Force officers intercepted it.
Each boat was around nine metres long and, according to the agency, could have been used to transport around 70 people across the Channel.
First such seizure from air freight
The NCA says this was the first interception of its kind involving air freight.
Deputy director of investigations Craig Turner said operations with international partners had intercepted more than 1,600 boats and engines. He said the agency assessed that seizures were raising equipment costs and reducing smugglers' profits.
The investigation continues.
Earlier shipment stopped at Felixstowe
The airport operation follows a separate seizure at Felixstowe on 18 July, when NCA officers and specialist Border Force search teams intercepted at least 25 inflatable boats and 25 outboard engines.
That equipment was in a shipping container arriving from China aboard a vessel whose next stop was Hamburg. Investigators believed the cargo would have been unloaded in Germany.
The NCA said those boats were ten metres long and could each have carried around 80 people. It explicitly said there was no suggestion that the ship's crew or operators knew what was inside the container.