The owners of an estate where two young golden eagles went missing have joined an appeal for information.

The birds, named Adam and Charlie, are said to have vanished within hours of each other from the Auchnafree Estate, near Dunkeld in Perthshire, on April 18.

The eagles' satellite tags stopped working and neither the birds nor the tags have been traced.

Auchnafree, a farming and sporting estate, said police conducted a search last month and were satisfied that its employees were not involved.

Estate spokeswoman Alix Whitaker said: "No-one knows what has happened to these birds and we would urge anyone with information to make contact with Police Scotland as soon as possible.

"We have also written to neighbouring estates to ask them to help.

"While the estate owns the land, we let out mixed shooting to tenants who take their wildlife conservation responsibilities very seriously."

Tenant Auchnafree Sporting said: "We see eagles frequently on the estate and have no problem with them. We assisted police with their investigation and wholeheartedly support the appeal for information."

The birds were being monitored by wildlife presenter and campaigner Chris Packham and Raptor Persecution UK as part of a study into the movements of young golden eagles in Scotland.

Charlie and Adam hatched at separate nests in the Loch Lomond & Trossachs National Park in 2017 and 2018 respectively.

Adam was named by Green MSP Andy Wightman, who said he was "shocked and devastated" to hear that the young eagle had gone missing.

Springwatch co-presenter Packham said in a statement: "We can't prove that harm has come to Adam and Charlie, nor who might have been responsible, but we can look at the circumstances, look at the science, look at the wider evidence and draw plausible conclusions.

"The Scottish Government has already acknowledged that illegal raptor persecution is an ongoing problem.

"How many more golden eagles do we have to lose before that same Government takes effective action?"

Mr Wightman suggested there was "organised criminal activity" taking place on Scotland's grouse moors and has written to First Minister Nicola Sturgeon calling for a step-up in prevention and detection of wildlife crime.

He said: "These disappearances are merely the latest in a long, long list of raptors to disappear in suspicious circumstances in Scotland.

"This latest outrage should be a wake-up call to the Scottish Government that for all their reviews, inquiries and reforms, rampant criminality remains in place across many of Scotland's driven grouse moors."

The Scottish Gamekeepers Association said it acts "robustly" where there is evidence that wildlife crime has taken place, with seven members expelled in as many years.

But a spokesman voiced concerns about missing satellite-tagged birds which are being monitored by non-independent agencies.

He said: "There is a need for everyone to better understand the discrepancy between independent figures verified by Police Scotland and government agencies, showing a clear and consistent pattern of declining raptor crime in Scotland, and cases which are brought by outside bodies on the back of missing satellite tags.

"Some of these outside bodies have both an investigative and a campaigning role which we feel can blur the line between seeking prosecutions and seeking publicity for campaigns, such as the present campaign to legislate or ban grouse shooting.

"That is why The Scottish Gamekeepers Association intends to petition Parliament so these tags can be monitored independently, giving Police Scotland, Scottish Government and the Scottish public greater openness and understanding of what is going on."

A Scottish Government spokesman said: "The disappearance of any bird of prey in suspicious circumstances is of concern and we would urge anyone with information to contact Police Scotland.

"We are determined to protect birds of prey and have established an independent group to look at how we can ensure grouse moor management is sustainable and complies with the law."

Anyone with information about the disappearance of Adam and Charlie is urged to contact Police Scotland on 101 or the RSPB's confidential raptor crime hotline on 0300 999 0101.