British political satirist and TV host John Oliver found a "better way" to make whistleblower Edward Snowden explain the mass surveillance programmes conducted by the US National Security Agency (NSA).

For an interview in HBO's Last Week Tonight show, Oliver met Snowden in Russia, where he has taken asylum after leaking millions of secret NSA documents to media.

Oliver wanted Snowden to explain the vast data collection techniques used by the US government, as the general public have little or no clues about them.

In a survey of more than 23,000 internet users conducted by the Centre for International Governance Innovation, just 60% have heard of Snowden, while merely 39% among them have changed their online behaviour.

"It's difficult for most people to even conceptualise," Snowden said in the interview, admitting the difficulty he has to defend his cause.

Oliver later prompted Snowden to explain the whole idea of US surveillance in terms of private explicit photographs which could be understood by many internet users. He also showed a video in which some Americans say they would not be happy if their private photos were floating around government offices.

"This is the most visible line in the sand for people: Can they see my dick?" Oliver said before handing over a folder with a picture of his genitals and asking Snowden to explain each NSA programme with regards to that picture.

"The good news is there's no programme named 'The Dick Pick' programme. The bad news is they're still collecting everybody's information, including your dick picks," Snowden said.

He also explained US surveillance programmes such as PRISM, Upstream and Mystic in connection with the pictures.

Watch the full episode of Last Week Tonight: Surveillance below.