Birds of prey being re-introduced to areas of the UK are under threat because they are being illegally killed, experts are warning.
Red Kite were reintroduced between 1989 and 1992
Breeds such as the red kite and hen harrier are being targeted, especially in areas managed as grouse moors, says the UK Raptor Working Group.
The group was established in 1995 to advise ministers over the issue.
Professor Colin Galbraith of the UK Raptor group said the persecution of raptors was a "disgrace".
Birds of prey have always been unpopular among gamekeepers and pigeon fanciers because they prey on red grouse in the uplands, racing pigeons, and pheasants prior to their release in the lowlands.
But over the last five years, the Joint Nature Conservation Committee and the country conservation agencies have been helping to implement the Working Group's recommendations, the UK Raptor Working Group says.
These included the launch by the police in 2004 of Operation Artemis, to target those responsible for the continuing illegal persecution of threatened hen harriers.
Red Kites have been persecuted for centuries, say conservationists
But, it said, the illegal persecution of birds of prey continues in many areas. Published research has shown that this is especially prevalent in areas managed as grouse moors.
Professor Colin Galbraith, co-chairman of the UK Raptor Working Group and director of Scientific and Advisory Services in Scottish Natural Heritage, said: "It is very pleasing to see so much progress as a result of the report and the vigour with which organisations now work together is encouraging.
"However, the illegal persecution of raptors remains a disgrace. It is important now to focus our efforts on combating this persecution in conjunction with the landowners, the police and other authorities."
The status of the hen harrier in England is now markedly worse than it was five years ago and it may cease to be a breeding species if the current level of persecution continues, the group says.
In some areas of Scotland, the re-establishment of the red kite continues to be jeopardised by illegal killing and each year brings further reports of the persecution of other raptors, notably golden eagles and peregrines.
One hundred red kites were reintroduced in both the Chilterns and north Scotland over three years starting in 1989.
In 2004, 215 pairs of the bird were recorded in the Chilterns, while in Scotland just 35 pairs were counted.
In 2003, the Royal Society for the Protection of Birds (RSPB) reported 143 cases of illegal shooting, trapping or nest destruction of birds of prey and 91 cases of illegal poisoning. The totals include the poisoning of 16 red kites.
Golden eagles are threatened by persecution in parts of mainland Scotland and some local populations face the prospect of significant decline unless action is taken, according to recent research published in the scientific journal Biological Conservation.
Grahame Madge of the RSPB said: "Unfortunately among some game keepers there remains a deep-seated attitude towards protecting their shooting interests and they see a bird of prey as a threat to the rearing of game.
"Even this year, we have already found cases of birds of prey poisoning. It is still a considerable problem, particularly in upland areas."