The British computer scientist who created the world wide web has said encryption cracking by UK and US spy agencies is "appalling and foolish".
Sir Tim Berners-Lee told the Guardian that the practice undermined efforts to fight cybercrime and cyberwarfare.
He called for a "full and frank public debate" on internet surveillance.
It comes as a parliamentary committee is due to quiz the heads of the UK's spying agencies - GCHQ, MI5 and MI6 - together in public for the first time.