The former head of the National Security Agency was the victim of an eavesdropping campaign himself, when a blogger overheard him on a train briefing against the Obama administration, and then wrote about it on Twitter.

Michael Hayden, who also once headed the CIA, was talking on his mobile phone after boarding a train to Newark, New Jersey, from Washington. He was giving an interview to journalists “on background”, whereby he would be quoted as a “former senior administration official”, when Tom Matzzie overheard him and immediately divulged the best bits on Twitter.

<noframe>Twitter: Tom Matzzie - Former NSA spy boss Michael Hayden on Acela behind me blabbing "on background as a former senior admin official" Sounds defensive.</noframe>

<noframe>Twitter: Tom Matzzie - Hayden talking about a famous blackberry now.</noframe>

<noframe>Twitter: Tom Matzzie - Hayden was bragging about rendition and black sites a minute ago.</noframe>

<noframe>Twitter: Tom Matzzie - Michael Hayden on Acela giving reporters disparaging quotes about admin. "Remember, just refer as former senior admin" <a href="https://twitter.com/search?src=hash&q=%23exNSAneedsadayjob" target="_blank">#exNSAneedsadayjob</a></noframe>

<noframe>Twitter: Tom Matzzie - On Acela: former NSA spy boss Michael Hayden just ended last of handful of interviews bashing admin.</noframe>

<noframe>Twitter: Tom Matzzie - On Acela listening to former NSA spy boss Michael Hayden give "off record" interviews. I feel like I'm in the NSA. Except I'm in public.</noframe>

<noframe>Twitter: Tom Matzzie - On Acela: phone ringing. I think the jig is up. Maybe somebody is telling him I'm here. Do I hide?</noframe>

<noframe>Twitter: Tom Matzzie - I think I'm safe. Just passed Philly. No rendition yet. Do I have the balls to ask him for a photo? <a href="https://twitter.com/search?src=hash&q=%23haydenacela" target="_blank">#haydenacela</a></noframe>

<noframe>Twitter: Tom Matzzie - Win <a href="http://t.co/tsJHqjv1LM" target="_blank">http://t.co/tsJHqjv1LM</a></noframe>

Eventually Mr Hayden was alerted to the reporting and towards the end of Mr Matzzie’s Tweeting, he approached him.

“Would you like a real interview?” Mr Hayden asked.

“I’m not a reporter,” Mr Matzzie replied.

“Everybody’s a reporter,” Mr Hayden said, according to The Washington Post, before posing for a photo with Mr Matzzie.

Mr Hayden later told The Post that he was not disparaging Mr Obama or the administration, saying Mr Matzzie had “got it terribly wrong”, dismissing the tweets as an inaccurate “story from a liberal activist sitting two seats from me on the train hearing intermittent snatches of conversation.”