At least six Thai activists and researchers who have been critical of the government have received the notification, reports TechCrunch.
The alerts have also been sent to a number of users in El Salvador.
Also Read | Samsung adds Pro Mode support for Galaxy S21 Ultra telephoto camera
After filing a lawsuit against the Israel-based company NSO Group, the developer of infamous Pegasus spyware, the tech giant has started sending threat notification alerts to victims of state-sponsored hackers, beginning with Thailand, El Salvador and Uganda.
The alert from Apple warned that the company believes "you are being targeted by state-sponsored attackers who are trying to remotely compromise the iPhone associated with your Apple ID".
"These attackers are likely targeting you individually because of who you are or what you do. If your device is compromised by a state-sponsored attacker, they may be able to remotely access your sensitive data, communications, or even the camera and microphone. While it's possible this is a false alarm, please take this warning seriously," the Apple alert read.
Also Read | 'Tech disruptor' Madhav Sheth gears up to make realme a global brand
Tech giant Apple on Tuesday filed a lawsuit against the NSO Group, seeking a permanent injunction to ban the Israeli company from using any Apple software, services or devices.
Apple admitted that a small number of its users may have been targeted by a NSO Group's exploit to install Pegasus on Apple devices.
"State-sponsored actors like the NSO Group spend millions of dollars on sophisticated surveillance technologies without effective accountability. That needs to change," said Craig Federighi, Apple's senior vice president of Software Engineering.
The Apple lawsuit also seeks redress for NSO Group's flagrant violations of the US federal and state law, arising out of its efforts to target and attack Apple and its users.