The Partnership for Action Against Wildlife Crime (PAW) Scotland say that to protect the native red squirrel species, there must be a programme of trapping and culling non-native greys.
The partnership warned that those who interfered with the traps could be inadvertently breaking the law, as it is illegal to release, or allow to escape, any captive grey squirrel.
They also said that those who released grey squirrels into different areas where they were trapped risked spreading a deadly squirrelpox virus to red squirrels.
Paul Wheelhouse, Minister for Environment and Climate Change and chair of PAW Scotland, said: "Unfortunately grey squirrels have spread so successfully that they have damaged the chances for our native reds.
"So that we don't lose the species, we have had to introduce methods to control greys."