GENEVA: An FBI demand that Apple unlock an iPhone risks setting a dangerous precedent that could have a chilling effect on human rights, the United Nations rights chief warned Friday.

Zeid Ra'ad Al Hussein's intervention came after Apple's largest rivals backed the tech giant's bid to resist the US government demand seeking to access the iPhone used by one of the attackers in a deadly rampage in San Bernardino, California in December.

“In order to address a security-related issue related to encryption in one case, the authorities risk unlocking a Pandora's Box that could have extremely damaging implications for the human rights of many millions of people, including their physical and financial security,” Zeid said in a statement.

Read: Apple ordered to hack San Bernardino shooter's iPhone

He warned that the FBI order would “set a precedent that may make it impossible for Apple or any other major international IT company to safeguard their clients' privacy anywhere in the world”.

The FBI wants to unlocked the iPhone used by Syed Farook, who was behind the San Bernardino massacre along with his wife Tashfeen Malik that left 14 people dead.

The agency has argued that by introducing encryption that can lock data, making it accessible only to the user, Apple and other tech companies are essentially creating “warrant-proof zones” for criminals and others that will cripple law enforcement and jeopardise public security.

Apple has in return said that the only way to unlock the handset would be to introduce a weakened operating system, which could potentially leak out and be exploited by hackers and foreign governments.

'Gift to authoritarian regimes'

Zeid said the FBI “deserves everyone's full support” in its investigation into what he described as an “abominable crime”.

But he added: “This case is not about a company -- and its supporters -- seeking to protect criminals and terrorists, it is about where a key red line necessary to safeguard all of us from criminals and repression should be set.

“There are many ways to investigate whether or not these killers had accomplices besides forcing Apple to create software to undermine the security features of their own phones. “It is potentially a gift to authoritarian regimes, as well as to criminal hackers.“

Zeid said encryption tools were widely used around the world, including by human rights defenders, civil society, journalists, whistle-blowers and political dissidents facing persecution and harassment.

“Encryption and anonymity are needed as enablers of both freedom of expression and opinion, and the right to privacy. Without encryption tools, lives may be endangered.“

Three tech associations representing Apple's main business rivals — including Google, Facebook, Microsoft and Yahoo — said Thursday they supported Apple's efforts to challenge the order.

“If the government arguments prevail, the Internet ecosystem will be weakened, leaving Internet users more vulnerable to hackers and other bad actors,” said a statement from the Computer and Communications Industry Association, which announced the joint brief with the Internet Association and the i2Coalition of Internet infrastructure firms.

But relatives of some of the San Bernardino victims backed the FBI bid in a legal brief filed in the court where the case is being heard.

They said Apple wanted to portray the debate as “one in which the privacy interests of millions of Americans are at stake in order to obtain sympathy for its cause.“

“What is implicated here is the United States' ability to obtain and execute a valid warrant to search one phone used by a terrorist who committed mass atrocities,” the brief said.