Apple Inc. CEO Tim Cook said in an early Monday morning email to employees that the U.S. government should withdraw its demand that Apple help the FBI hack a locked iPhone used by a shooter in the San Bernardino attack.

The message, subject-lined "Thank you for your support," is accompanied by an online question and answer page that reiterates many of the comments Cook made in a public letter after a magistrate judge's order last week. His communication to staff also brushes aside several key government claims made in Friday's filing, including an assertion that the company was acting out of business interests in saying it would not co-operate with an investigation of the California shootings by the FBI.

The comments from Apple and its CEO cap a week of back-and-forth filings and statements involving the Justice Department, FBI and Apple, after a U.S. magistrate ordered the company to break its iPhone security protocols to assist federal officials probing the San Bernardino shootings.

The emerging legal fight has sparked a debate on government power, privacy, digital rights, public safety and security set in connection with the Dec. 2 shootings.

The county-owned iPhone was used by Syed Farook, who along with his wife Tashfeen Malik, killed 14 people during the attack.

"Dangerous precedent"

Cook states in the letter to employees that the company has "no tolerance or sympathy for terrorists" and believes abiding by the judge's order would be unlawful, an expansion of government powers, and would set a dangerous precedent that would essentially create a backdoor to the encrypted iPhone.

"This case is about much more than a single phone or a single investigation," Cook wrote, "so when we received the government's order we knew we had to speak out."

"At stake is the data security of hundreds of millions of law-abiding people and setting a dangerous precedent that threatens everyone's civil liberties."

The question and answer posting acknowledges that it is technically possible for Apple to do what the judge ordered, but that it's "something we believe is too dangerous to do."

Apple also points to the difficulty of keeping such a "master key" safe once it has been created. The government has said that Apple could keep the specialized technology it would create to help officials hack the phone — bypassing a security time delay and feature that erases all data after 10 consecutive, unsuccessful attempts to guess the unlocking passcode. This would allow the FBI to use technology to rapidly and repeatedly test numbers in what's known as a brute force attack.

If the company's engineers were to do as ordered, Apple would do its best to protect it the technology, but Cook said the company "would be relentlessly attacked by hackers and cybercriminals."

Friday deadline for court reply

"The only way to guarantee such a powerful tool isn't abused and doesn't fall into the wrong hands is to never create it," Apple states in the memo. The company has until Friday to formally protest the ruling in court.

FBI Director James Comey said in an online post Sunday that Apple owes investigative cooperation to the San Bernardino victims and said the dispute wasn't about creating legal precedent. The FBI "can't look the survivors in the eye, or ourselves in the mirror, if we don't follow this lead," Comey said.

"We simply want the chance, with a search warrant, to try to guess the terrorist's passcode without the phone essentially self-destructing and without it taking a decade to guess correctly. That's it," Comey wrote. "We don't want to break anyone's encryption or set a master key loose on the land."

Cook said the government should withdraw its demand to the judge and form a group to discuss the issues brought up by this case. He said Apple would participate in such an undertaking.

Apple said it has continued to co-operate and has tried to help the government since the Justice Department court filings.

Much of the rhetoric has focused on whether the Justice Department would actually focus its investigation on a single phone, or whether its move in court represents an attempt to set a precedent for technology sharing that would ultimately be used on multiple phones. This high-profile case would not have existed if the county government that owned the iPhone had installed a feature on it that would have allowed the FBI to easily and immediately unlock the phone.

San Bernardino County had bought the technology, known as mobile device management from MobileIron Inc., but never installed it on any of the inspectors' phones, including Farook's, said county spokesman David Wert said. There is no countywide policy on the matter and departments make their own decisions, he said.

The service costs $4 US per month per phone.