Edward Snowden
Snowden worked as a contractor for the NSA before choosing to release a trove of classified documents in 2013 Reuters

Edward Snowden, the former National Security Agency (NSA) spy-turned-whistleblower, has slammed the FBI for claiming the agency doesn't have the technical capability to break into the iPhone 5C at the centre of the ongoing legal battle with Apple.

Speaking during a discussion at Common Cause's Blueprint for Democracy conference in Washington on 8 March, he said via video link: "The FBI says Apple has the 'exclusive technical means' to unlock the phone. Respectfully, that's horses**t."

Snowden worked as a contractor for the NSA before choosing to release a trove of classified documents in 2013 that exposed the vast spying apparatus used by global intelligence services including the CIA, NSA and UK's GCHQ.

The most recent encryption debate has now reached the US federal courts and law enforcement has told judges the only way to access the iPhone recovered from the possessions of San Bernardino shooter Syed Rizwan Farook is to force Apple to write code to circumvent its security.

Snowden further explained his position on Twitter by linking to a post on the American Civil Liberties Union (ACLU) website that outlines various methods the FBI could use to bypass the auto-erase function of the device using known computer tactics.

The post states: "The FBI wants us to think that this case is about a single phone, used by a terrorist. But it's a power grab. Law enforcement has dozens of other cases where they would love to be able to compel software and hardware providers to build, provide, and vouch for deliberately weakened code. The FBI wants to weaken the ecosystem we all depend on for maintenance of our all-too-vulnerable devices."

Meanwhile, questions have also been raised about why the FBI did not approach the NSA itself for help in gaining access to the iPhone – after all, the agency is highly regarded as employing some of the best cryptography and computer experts in the world.

While there have been numerous arguments put forward as to why the FBI appears to be going it alone, some US politicians have raised concerns the agency could be exploiting the Islamic-State inspired San Bernardino tragedy for political gains.

US Congressman John Conyers told a House Judiciary Committee on 1 March: "I would be deeply disappointed if it turns out that the government is found to be exploiting a national tragedy to pursue a change in the law."

Conyers was referencing a leaked email written by the intelligence community's top lawyer, Robert Litt dated August last year that said: "Although the legislative environment is very hostile today, it could turn in the event of a terrorist attack or criminal event where strong encryption can be shown to have hindered law enforcement."

According to The Washington Post, the email added there would be value in "keeping our options open for such a situation".