WASHINGTON — More than 100 activist organizations, security experts and industry groups warned Tuesday against efforts to force tech companies to weaken encryption, saying any such requirement would help hackers, criminals and authoritarian governments.

The warning came in a letter to top law enforcement officials in the United States, Britain and Australia, responding to an effort by those countries to gain special access to encrypted content on Facebook and its messaging services.

The signatories said any special "backdoor" access would make all communications less secure.

"These exceptional access mechanisms for law enforcement agencies would be the same 'backdoors' that provide an opportunity for terrorists, criminals, and other parties to gain unauthorized access," said the letter endorsed by the American Civil Liberties Union, Amnesty International, Human Rights Watch and other organizations and individuals.

"This is because technologists cannot build systems that are inherently able to tell when 'bad' people use them, just as engineers cannot design sidewalks and highways to crumble underneath the feet of certain people. In both cases there is a chance that they would build something that is unsafe for all users."

The letter marks the latest in a long debate over law enforcement access to encrypted communications.

A joint letter in October signed by US Attorney General William Barr, British Home Secretary Priti Patel and Australian Home Affairs Minister Peter Dutton urged Facebook to give authorities the ability to circumvent encryption used in its messaging services.

The officials said that strong encryption used by Facebook and others makes it more difficult for law enforcement to detect criminal acts including terrorism and child pornography, and that a move to implement "end-to-end" encryption on its Messenger platform could make matters worse.

The company already encrypts WhatsApp messages from end-to-end — meaning that only the sender and recipient can read the message — and is working to extend the technology to other apps in its family, including Messenger and Instagram.

"Facebook has not committed to address our serious concerns about the impact its proposals could have on protecting our most vulnerable citizens," said the October letter.

Tuesday's letter said there is little evidence that weaker encryption or special access would have a significant impact on law enforcement.

"If companies build law enforcement access mechanisms into encrypted products, some targets of investigations will simply move to using different encrypted services," the letter said.

It also said that special access demands from countries such as the US, Britain and Australia would "embolden repressive and authoritarian regimes in their attempts to pressure messaging apps and device manufacturers to build surveillance capabilities into their products and services." — AFP