The CIA has lost dozens of informants in foreign countries, according to a report published Tuesday.

The disclosure that a large number of individuals recruited to spy for the US had been killed, captured or compromised in recent years was made in a top secret cable obtained by the New York Times. The cable was distributed to every CIA station and facility around the world.

Oppositional intelligence agencies in Russia, China, Iran and Pakistan have been hunting down US intelligence assets and in some cases turning them into double agents, the Times reported.

The memo said the success of other intelligence agencies is due in part to their increasingly sophisticated technologies, including biometric scans and facial recognition tools that have allowed them to track CIA officers and, in some cases, discover the identities of informants.

The memo urged case officers to not only be mindful of evading those technologies, but to also be sure to vet their recruits, and placed a special emphasis on reminding officers that they are underestimating their adversaries.

Former officials who spoke to the Times said the CIA has grown rusty at recruiting informants in foreign governments after spending decades focused on post-9/11 counterterrorism.

Rather than kill or capture US informants, some foreign governments have been turning them into double agents and using them to provide the CIA with disinformation, and the former officials said Pakistan has shown a marked capacity for doing it.

Developing networks in Pakistan has become more important in the wake of the collapse of the US-backed government in Afghanistan, and the Times said, "learning more about Pakistan’s ties to the Taliban government and extremist organizations in the region is going to become ever more important."

- As a result, the pressure is once again on the C.I.A. to build and maintain networks of informants in Pakistan, a country with a record of discovering and breaking those networks - it said.

- Similarly, the focus by successive administrations on great power competition and the challenges of China and Russia have meant that building up spy networks, and protecting those sources, is more important than ever - it added.