New Delhi, Oct 6 (IANS): The CIA has admitted that too many informants are being killed, captured or turned in a top secret memo to their spies across the world, as per a report in Daily Mail.

The unusual cable, sent to all CIA stations and bases, said the counter-intelligence mission centre had analysed dozens of cases over the last several years.

The memo gave an exact number of informants killed, classified information not usually shared in such cables, according to the New York Times.

Former officials have also disclosed that China and Iran cracked the agency's classified communications system, or 'covcom', and executed informants in those networks while others had to be extracted and resettled.

The memo reprimands spies for poor tradecraft, being overly trusting of sources, underestimating foreign intelligence agencies and 'putting mission over security' by moving too fast and not paying enough attention to potential risks.

Russia, China, Iran and Pakistan have had success in hunting down informants in recent years -- and in some cases turning them into double agents.

In Iran and China, some intelligence officials believe that Americans provided information to the adversarial agencies that could have helped expose informants.

The rival counterintelligence agencies are utilizing biometric scans, facial recognition, AI and hacking tools to track CIA officers to discover their sources.

In 2019, former CIA officer Jerry Chun Shing Lee was sentenced to 19 years in prison for providing secrets to the Chinese government, which they then used to arrest and execute at least 20 of his fellow agents.

US officials suspect China shared the information Lee gave them to Russia, who used it to expose, arrest and kill American spies.

Those findings led the CIA to temporarily shut down human spying in China and re-evaluate how it communicates with intelligence assets worldwide, the report said.