Michael Hayden
Former NSA and CIA chief Michael Hayden (Reuters)

The former head of the NSA, the US intelligence agency accused of scooping on millions of people around the world, had an off-the record interview he was giving as an anonymous source tweeted live by a man sitting in front of him on a train.

Tom Matzzie, a renewable energy entrepreneur and a progressive activist, happened to be sat a few seats away from Michael Hayden on a New York-bound train, when the former top US spy started talking loudly on the phone about President Barack Obama, his phone and American intelligence activities.

As soon as Matzzie realised the loud passenger was in fact the former CIA and NSA chief, he started tweeting.

For about 20 minutes Mattzie went on tweeting accounts of Hayden's interview, which he said touched on numerous intelligence issues, ranging from Obama's choice of using a reportedly non-safe blackberry as personal mobile phone to the US snooping on its European allies.

At some point the former chief spy received a second phone call alerting him he was being spied on.

Instead of going berserk, Hayden walked up to Mattzie, offered him a proper interview, chatted about the fourth amendment protecting US citizens against government intrusion and also posed for a picture with his snoop.

Mattzie is an activist with MoveOn, a US liberal advocacy group. The curious incident happened on an Acela express train popular with politicians and lobbyists that runs from Washington to New York.

Tom Matzzie NSA
Former NSA and CIA chief Michael Hayden poses with Tom Matzzie (Twitter)