A senior officer said yesterday that the growing illicit market for rare animals and plants was worth pounds 4bn a year. Some of the most sought-after species are being sold illegally through British pet shops.
Paul Andrews, environmental crime specialist at Interpol, which is based at the National Criminal Intelligence Service, said: "Britain is one of major purchasing countries for these rare species and we have criminals here brokering sales for the markets in America and Japan."
British species are also being targeted. Dutch and German police have warned that organised gangs of traders in birds of prey are taking carefully planned trips to Scotland to raid the nests of golden eagles, red kites and peregrine falcons. The Royal Society for the Protection of Birds said last night that there had been a marked increase in such thefts, with 40 peregrine falcons stolen last year. The world's most wanted rare bird is the Lear's macaw, of which only 98 are believed to still exist.
Three of the birds - which are worth around pounds 80,000 each - were found in raids on houses in Yorkshire in April.
It is believed they were brought to Britain from Australia, South America and Malaysia.
During the raids, Customs officers also seized 10 palm cockatoos and several yellow-tailed and red-tailed black cockatoos, both endangered species, and worth up to pounds 10,000.
One of the most frequently smuggled exotic birds is the hyacinth macaw, which will fetch around pounds 20,000. The traders estimate that they need to smuggle 12 eggs to have a good chance of one surviving.
Many of the bird smugglers wear customised jackets beneath their outer clothing. Each jacket contains up to 20 pouches in which the rare eggs are placed in the knowledge that they will not show up on X-ray machines.
The illegal trade in tortoises is also buoyant. Customs officers at Dover and Heathrow airport have seized India Star tortoises, which are usually smuggled in hand luggage and can be worth pounds 1,000 each.
The RSPB said last night that German falconers were believed to be mainly responsible for the loss of 40 peregrine falcons reported stolen last year. There are only 1,300 pairs in the UK.
Guy Shorrock, investigations officer for the RSPB, said: "During the last two breeding seasons there seems to have been a renewed interest in our native peregrines, particularly the ones from Scotland. There are a lot of indications that a number of birds are being taken and laundered on the Continent, especially in Germany."
The thieves often come in camper vans, equipped with incubators run from the vehicle's generator. They take the birds back to the Continent and pass them off as captive-bred.
Mr Shorrock said that the internal UK market for peregrines had almost died out following the prosecution of a several dealers through DNA testing of the birds.
But falconry is highly popular in Germany, where dealers also have contacts with Arab falconers prepared to pay thousands of pounds for wild-bred birds. He said: "German and Dutch falconers are coming over to Britain themselves but there are a number of people here who are willing to help for money."Two men from the Netherlands are facing charges in relation to alleged attempts to buy peregrine falcons in contravention of the Convention on International Trade in Endangered Species.
Later this year Interpol is due to publish a report on the international trade in primates based on a world-wide police survey of reported thefts and seizures.