More than 800,000 songbirds, including blackcaps, robins and garden warblers, are estimated to have been illegally killed last autumn on a British military base in Cyprus.

New research by the RSPB and BirdLife Cyprus identified a record number of illegal and virtually invisible “mist” nets set to trap migrating birds on British territory in the Mediterranean. The number of nets discovered on Ministry of Defence (MoD) land in Cyprus has increased by 183% since monitoring began in 2002.

Small-scale trapping of songbirds birds for human consumption has been practiced for centuries in Cyprus, but despite it being outlawed in 1974 it is now carried out on an industrial scale. The report estimates that more than 2.3 million birds, from approximately 153 different species, were killed across the whole of Cyprus last autumn, with the birds served as traditional “ambelopoulia” in island restaurants.

“The British base is the number one bird-killing hotspot on the whole island of Cyprus,” said Martin Harper, RSPB conservation director, calling on the British government to help embattled military base police stop the illegal killing. “Many much-loved garden bird species are being trapped and killed for huge profit by criminal gangs.”

Trappers have planted non-native Australian acacia trees on MoD land to lure passing birds. They then place long lines of netting in the trees to catch the birds.

Long lines of netting placed in trees to illegally catch birds. Photograph: RSPB/PA

The military administration removed 54 acres of acacia over two years but were forced to virtually abandon the clearance last autumn – removing just seven acres – after trappers organised large protests and a dramatic blockade of the base.

Trappers also deploy electronic calling devices over the base at night to lure the birds, and the conservation charities said they feared some parts of the military base were becoming a no-go area for the committed, but outnumbered, local police force.

“The trappers’ brazen prevention of the removal of their criminal infrastructure from MoD land could never be tolerated here in the UK,” said Harper. “The UK government must therefore provide enforcement support to help the base authorities respond to the trappers and safely remove the remaining 90 acres of acacia so that they cannot be used to kill hundreds of thousands more birds.”

A spokesperson for the MoD said: “We’re committed to tackling illegal bird trapping and the RSPB has recognised our increased enforcement activity, which has led to a record number of arrests, equipment seizures, prosecutions and fines. For the second year running we’ve halted the rising trend in the numbers of birds being killed by poachers and we continue to work with the RSPB and Birdlife Cyprus to implement a long-term strategy to reduce this number.”

Martin Hellicar, director of BirdLife Cyprus, said: “We cannot ignore the distasteful fact that the restaurants serving trapped birds operate within the Cyprus Republic. Enforcement against these law-breaking restaurants has been limited – at best – in recent years, and the Cypriot authorities must change this. We need a clamp-down on the illegal market supporting this wildlife crime, something the European Commission has called for, repeatedly.”

Trapped migrating birds are preserved in vinegar or cooked before being served in restaurants. Prosecutions are difficult because these plucked, beheaded birds cannot easily be identified or proven to have been acquired illegally.

But conservation scientists in Cyprus have recently developed a DNA barcoding database of resident birds and commonly trapped species to enable the accurate identification of illegally killed birds. It is hoped that the increased risk of prosecution from the use of DNA barcoding as a forensic investigative tool may deter restaurants from serving the birds.