Sony Pictures Entertainment employees and staffers have again received threatening email messages from online hackers Friday, warning the group will inflict harm not only on them but their families as well.

The group, calling itself the Guardians of Peace (GOP), has threatened the employees who did not assist the GOP that their families could land  in harm's way.

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The staffers were ordered to turn off their mobile phones and tablets as the Federal Bureau of Investigation (FBI) have stepped in to investigate the matter.

The FBI said they have been informed of the latest GOP threat to Sony employees and are looking into other possible group of hackers aside from the GOP.

"The FBI is aware of threatening emails that have been received by some employees at Sony Pictures Entertainment," said FBI press officer Joshua Campbell in a statement.

Campbell said the agency will continue to investigate the matter and will identify the person or group responsible for the recent attack on the Sony Pictures network.

"We continue to investigate this matter in order to identify the person or group responsible for the recent attack on the Sony Pictures network."

Sony has had computer security teams working round the clock  on rebuilding the network after its initial hack was found out on Nov. 24.

Employees have been instructed to stay off emails and avoid using the company wifi for the meantime that the servers are being repaired.

The two assaults came after Sony had been busy all week shifting email to new servers, ordering employees to change passwords and going back to the basic use of punch card for the employees to compute their salaries.

Daniel Tentler from the security firm Carbon Dynamics said the massive file dumped on Sony computers was more than 100 gigabytes.

Tentler said the posting was titled "Gift of GOP for 3rd Day:Financial Data of Sony Pictures."

Sony has scrambled to thwart another attack by the GOP but this proved to be insufficient. Messages from the postings have landed on the employees' inboxes and Sony has expressed alarm on the possibility of a leak of their private data into the public domain as warned by the hackers.

"The data to be released next week will excite you more," the message read.

Experts said that although the message has yet to be deciphered, GOP said it contained "many pieces of confidential data" of Sony.

The message also directed the readers to an email address if they "love peace" and want to become a member. The address directed them to a site that gives users anonymous email addresses.

TagsSony Pictures, GOP, FBI, hackers