Notorious computer security pioneer John McAfee has used a surprise appearance at a hacking conference to warn of threats against "freedom" thanks to privacy issues with technology.

Speaking at Def Con in Las Vegas, Mr McAfee called on hackers to "make a stand" against companies that seek highly personal information.

He blamed laziness for the spread of apps and websites that glean information from users.

"We'd rather be safe, secure and comfortable than actually live," he said.

In 2012 Mr McAfee was accused of murdering his neighbour while living in Belize. He fled the country soon after and denies the charges.

Video journalist: Dave Lee