Los Angeles (AFP) - The FBI has managed to unlock the iPhone used by one of the San Bernardino attackers, officials said Monday, ending a contentious court case with Apple.

"Our decision to conclude the litigation was based solely on the fact that, with the recent assistance of a third party, we are now able to unlock that iPhone without compromising any information on the phone," US attorney Eileen Decker said in a statement.

In a court filing asking that the case be dismissed, federal prosecutors said the US government had "successfully accessed the data stored on (Syed) Farook's iPhone and therefore no longer requires assistance from Apple Inc."

Apple, backed by a broad coalition of technology giants like Google and Facebook, was fiercely opposed to assisting the US government in unlocking the device on grounds it would have wide-reaching implications on digital security and privacy.

Farook and his wife Tashfeen Malik killed 14 people in San Bernardino, California on December 2 before dying in a firefight with police.