Plans to bring beavers back to Scotland have taken another step forward.
Up to 20 beavers may be involved in the trial
Ministers' wildlife advisers say the way is now clear to approve proposals for a colony in a woodland reserve at Knapdale, in Argyll.
Scottish National Heritage experts say there is nothing now to stop a licence being granted to allow the mammals to be reintroduced.
But some landowners have complained that the proposals could cause damage to the environment.
Up to 20 beavers would be involved in a seven-year trial, if the plans are agreed.
They would be brought from Norway for release as early as spring next year, after being kept in quarantine over the winter.
The animals have been extinct in Scotland for about 400 years.
Wildlife enthusiasts have been trying to bring them back for at least the last three decades.
A formal application for a licence to reintroduce beavers to woodland in Argyll was made in 2000 but ministers in Edinburgh took two years to ask for more information.
Environmentalists at Scottish Natural Heritage now say they have written to ministers answering all the outstanding questions and hope to have a licence by May.
Some landowners fear the animals - which they describe as "huge rats" - will be destructive pests, causing damage to local enterprises and the environment.
James Withers, of the National Farmers Union of Scotland, said: "Beavers haven't been in Scotland for 400 years.
"There's little evidence to show the species they're planning to introduce was ever in Scotland in the first place.
"We're talking about an alien species, a species that potentially we can't control once released. That's a huge worry for the farming industry."
"There's potential for them to breed and there's potential for them to actually undo some of the good environmental work that's been done, particularly in forestry in the area."
Colin Galbraith, of Scottish Natural Heritage, said: "We are convinced beavers were here in Scotland.
"We think it's right we undertake a scientific trial, closely monitored, with all the animals marked individually with little radio tags so they can be tracked around.
"We should know where they are at any one point in time. That should help allay a lot of the fears that we will not know where the animals were.
"It's not a large number. They will be tracked, so we should be able to catch them and take them back out if anything were to go wrong. But we really don't think it will.
"We want to keep talking to those people who oppose the trial, to involve them in the design and to involve them in how it runs in the years ahead."
Norman Milne, of the Scottish Wildlife Trust, added: "There's strong historical evidence that the beaver was native to Scotland from Berwickshire to Inverness and through the selfish actions of man was wiped out.
"It's more than just about introducing an endearing furry mammal back into Scotland. It's about all the other benefits the beaver brings with it, such as the creation of wetlands.
He continued: "There is a shortage of that habitat in Scotland. And beavers bring benefits to other wildlife.
"We believe this is a science species worth reintroducing. Other European countries have been doing it since the 1920s. This is not a new road we're taking."
Mr Milne said: "We're hugely excited about this project. We welcome a careful examination of reintroducing any extinct species back into Britain.
"But it needs to be done on a case by case basis and looked at very scientifically to weigh up all the pros and cons."