"Detekt is the first tool to be made available to the public that detects major known surveillance spyware," Amnesty said in a statement, providing a link for free downloads of the software.
    
It is being launched together with Digitale Gesellschaft in Germany, Electronic Frontier Foundation in the United States and Privacy International in Britain, Amnesty said.
    
"Governments are increasingly using dangerous and sophisticated technology," Marek Marczynski from Amnesty was quoted as saying.
    
The surveillance "allows them to read activists and journalists' private emails and remotely turn on their computer's camera or microphone to secretly record their activities," he said.
    
"Detekt is a simple tool that will alert activists to such intrusions so they can take action."
    
Amnesty's website had a copy of Detekt's warning notice, reading: "Danger! I managed to identify the potential presence of some spyware!
    
"You should turn off this computer, never connect it again to the Internet or any external device and seek assistance," it said.