Bill Ferguson is the grey squirrel control officer for the Central Borders Red Squirrel Network
A grey squirrel control co-ordinator in southern Scotland has said their "complete extermination" is the only way to protect red squirrels in the area from a deadly virus.
A number of cases of squirrelpox have been confirmed in the Borders and other parts of the country in recent weeks.
Bill Ferguson of the Central Borders Red Squirrel Network said it meant there was no other option to stop the spread of the disease than "eradication of the grey squirrel".
He said the public could also play its part by taking down any bird feeders used by grey and red squirrels for about three weeks and disinfecting them before putting them back out.
Ferguson said the only way to protect the reds was to trap and kill the greys
Squirrelpox is a carried by grey squirrels but is deadly to their red cousins.
"Unfortunately, the only way to control this is eradication of the grey squirrel," said Ferguson.
"There is no vaccine or any other help we can afford the red squirrels other than eliminate the greys from the area - we can't have both.
"Unfortunately, getting rid of the greys is the only way we can currently protect the red squirrel."
He said a contraceptive for grey squirrels was being developed which would see them "die off naturally" but until it was available, trapping and killing was the only option.
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"Complete extermination is the only way currently that we can preserve our native red squirrel," he said.
"Unfortunately there is no other answer.
"As long as the grey squirrel remains it will carry the pox virus which is fatal to our native red."
He said he understood people might think it was a step too far but they could only follow "scientific evidence".
"The elimination of the greys, it's done in a humane manner and it alleviates the threat to the reds," he added.
He urged estate owners to "do their bit" by controlling greys and also the public to take down any bird feeders being used by reds and greys.
Grey squirrels were introduced to Britain from North America in the 19th Century.
Opponents of killing them argue that squirrel pox is only one of a number of diseases which can kill red squirrels which have similar symptoms.
They also say that its method of transmission is such that they are much more likely to get it via fellow reds rather than from greys.