Numerous dead migrant birds shot by poachers were today discovered by the German-based Committee Against Bird Slaughter (CABS) on the Dwejra Lines.
The organisation in a statement there were seven freshly-shot bee-eaters, two swifts, a Sardinian warbler and the remains of two marsh harriers.
All are protected in Malta.
There were also several dead racing pigeons, one wearing the ring of a local racing pigeon club.
CABS said the birds were at the bottom of a defensive ditch, some five metres deep, constructed by the British in the 19th century.
Hunters had been observed in the area shooting at protected species on several occasions in the past few days. Some of the incidents were filmed by a CABS patrol and the video material and the dead birds were handed over to the Administrative Law Enforcement police.
Criminal proceedings are being initiated, Cabs said.
"We believe that many more dead birds can be found in the ditch," press officer Axel Hirschfeld said.
CABS has been operating on Malta since Friday in the framework of their autumn bird protection camp Operation Safe Voyage.
Civil liaison officer David Conlin said: "We deploy six teams to the countryside daily, working closely with the ALE".
The conservationists said they have already recorded numerous violations of Maltese hunting law and European bird protection guidelines.
These included shooting at birds of prey, the use of electronic decoy devices and weapons capable of firing more than three shots in succession.
Illegal hunting was also observed after 9 p.m. and on Sunday afternoon.
A full interim report, as well as the video material shot by CABS to date, will be made public next week, CABS said.
RECORD NUMBER OF VOLUNTEERS MONITOR BIRD MIGRATION
Meanwhile, BirdLife Malta in a separate statement said the biggest ever Raptor Camp kicked off this afternoon with the first teams of bird watchers going out into the countryside to monitor bird migration and deter illegal hunting.
The camp will run until the 2nd October and during this period 66 international volunteers from ten countries; Canada, Croatia, Denmark, Finland, Germany, Ireland, Latvia, Netherlands, Poland, and the UK will take part.
The camp is timed to cover the peak migration period for raptors when many of these birds stop overnight in Malta, to rest while on their autumn migration to warmer climates. Although raptors are protected by law they are highly prized by hunters and form the majority of shot protected birds.
"Scientific ringing studies have confirmed that raptors shot in Malta come from at least four of the countries Raptor Camp volunteers come from; Finland, Germany, Latvia and Poland," BirdLife said.
"Since the start of the opening hunting season BirdLife Malta has received daily reports of illegal shooting, several birds have been photographed in flight with gunshot damage, and six shot protected birds have been received by the organisation," BirdLife said.
It said that one of the main problems in countering the illegalities was that the ALE unit was under-resourced.
During the 2011 spring hunting season the European Commission requested an increased police presence in the countryside and ALE numbers were temporarily increased to 43 (from 20), after around 5,600 hunters applied for spring hunting licenses.
"There are nearly twice that number of hunters licensed for the autumn hunt, but without pressure from the Commission it is unlikely that ALE numbers will be increased proportionately," said Nicholas Barbara, BirdLife Malta Conservation and Policy Officer.