Edward Snowden has set out the case for Barack Obama granting him a pardon before the US president leaves office in January, arguing that the disclosure of the scale of surveillance by US and British intelligence agencies was not only morally right but had left citizens better off.

The US whistleblower's comments, made in an interview with the Guardian, came as supporters, including his US lawyer, stepped up a campaign for a presidential pardon. Snowden is wanted in the US, where he is accused of violating the Espionage Act and faces at least 30 years in jail. 

Speaking on Monday via a video link from Moscow, where he is in exile, Snowden said any evaluation of the consequences of his leak of tens of thousands of National Security Agency and GCHQ documents in 2013 would show clearly that people had benefited.