British MPs and judges are at risk of "manipulation by foreign governments and agencies" as a result of the Adult FriendFinder hack, security expert John McAfee has told Sky News.

Nearly four million users' details, including their sexual preferences, email addresses and in some cases nude photos, were leaked in late May.

Mr McAfee, the founder of McAfee, the anti-virus software manufacturer, said the hacker - known as ROR(OG) - who carried out the attack had shown him the complete database.

He told Sky News that three MPs and four judges are included in the database, and the hacker is trying to sell the information for $20m.

"Imagine the repercussions for the UK," Mr McAfee said. "I think someone's gonna pay the $20m and just take the whole thing.

"It not only opens up four million lives to devastation, it opens up the citizens of countries of those involved."

Mr McAfee said it was possible for passengers to hack into a passenger plane from their seat.

"It is extremely possible and it did in fact happen," he said.

Referring to his "close personal friend" Chris Roberts, who claimed he had gained access to the engine controls of a United flight via its in-flight entertainment system, Mr McAfee said "he endangered no lives whatsoever. He showed a massive hole in our understanding."

Aviation experts and plane manufacturers have disputed whether the hack is possible.

Speaking to Sky News ahead of a speech at Infosecurity 2015, a cybersecurity event in London, Mr McAfee attacked mooted plans for the Government to force companies to use weakened encryption, as part of the new Investigatory Powers Bill - the so-called snooper's charter.

Mr McAfee argued that any weakening of encryption would ultimately help criminals.

"All you're doing is formalising and facilitating the hacker community," he said.

"State surveillance is the greatest threat to our privacy. Hackers are not looking into our lives to make sure that we're living proper lives.

"They're into our lives to make money. The Government is into our lives to make sure we're behaving. There's a major difference. I don't want to be made to behave. Good god, I'm 70 years old, I no longer need a mother."

Mr McAfee said his company Future Tense Central would be partnering with Demonsaw, a social encryption company started by a programmer at Rockstar Games, the maker of the Grand Theft Auto series.

He said if the Government compelled his company to weaken their encryption, he would refuse.

"We would take it elsewhere. I have been in this business long enough to know that I would be doing no one a service by submitting to that demand. I'm not helping the British people, I'm hurting them in the long run."

After selling his stake in McAfee Inc in 1996 (the company was subsequently bought by Intel), Mr McAfee founded several other ventures, before moving to Belize.

In April 2012, he was arrested there for drug manufacturing and possession of an unlicensed weapon, but released without charge.

In November, he fled the country after police named him as a person of interest in a murder investigation.

Today, he lives in the US and travels with a bodyguard, who was present at the interview with Sky News.

"In Belize, I exposed corruption at the highest level within the government, which resulted in an attempt on the life of my wife and I, on 12 September 2013, and there have been numerous other attempts since then," he said.

"I have threats. And at the same time, I'm out talking my mind. I'm nearly 70 years old, I'm not going to shut up."