The FBI has said it may be able to unlock the iPhone of San Bernandino terrorist Rizwan Farook without Apple's help.

Apple confirmed that a court hearing scheduled for today (Tuesday) was postponed at the request of the US Department of Justice (DoJ). The DoJ had previously ordered Apple to help the FBI in unlocking Farook's phone to assist its investigation.

According to a court filing, "an outside party" said it may have a way of getting access to the phone without needing Apple.

"Testing is required to determine whether it is a viable method that will not compromise data on Farook's iPhone," a court filing said.

"If the method is viable, it should eliminate the need for the assistance from Apple."

Apple has so far stood its ground and refused to cooperate with the DoJ's court order, stressing that it would compromise the security and data of hundreds of millions of iPhone users around the world. Some of the world's biggest tech firms have given their support to Apple, with some even submitting an amicus brief - a document that allows parties that are not involved in a court case, but could be affected by its outcome, to have a say.

Earlier this month, Apple accused the DoJ of running a "smear campaign" against it, painting the tech giant as "evil" and "anti-American".

The legal battle centres around the iPhone of gunman Rizwan Farook, who killed 14 people and injured several others in California in December last year. The FBI wants access to his iPhone to support its investigation. iPhone have a security feature which deletes all files and data on the device if a passcode is incorrectly entered 10 times, if the user decides to use it. The FBI believes Farook used this feature.

The FBI wants two things from Apple. Firstly, it wants Apple to remove the 10 guess limit before data is deleted. And secondly, it wants Apple to help develop a method of automatically inputting thousands of possible combinations quickly.