Nigel Farage is facing strong criticism from Jewish organisations and a series of other groups after it emerged he repeatedly took part in interviews with a far-right US talkshow host, during which the Brexit party leader openly discussed conspiracy theories, some of which have been linked to antisemitism.

A Guardian investigation has found Farage has appeared at least six times on the show of Alex Jones, who was sued by bereaved parents after claiming a US school shooting was faked, and was banned permanently from Facebook last week.

Among those expressing alarm at the spread of conspiracy theories is a father whose six-year-old son died in the 2012 Sandy Hook school shooting, and a man whose son died in the London bombings on 7 July 2005, which Jones has claimed were a government plot.

Farage, who led Ukip for many years, quit the party last year because he said he disliked its hard-right, anti-Islam stance under Gerard Batten. However, the website that Jones fronts, Infowars, regularly features anti-Islam stories.

In his various appearances on Jones’s show, Farage discussed themes commonly associated with an antisemitic conspiracy theory that Jewish financiers are behind a plot to replace nation states with a global government.

In the six identified interviews, which date from 2009 to last year, Farage, whose Brexit party is leading polls for the upcoming European elections, repeatedly uses words and phrases such as “globalists” and “new world order”, which regularly feature in antisemitic ideas.

In the interviews, Farage also says:

Members of the annual Bilderberg gathering of political and business leaders are plotting a global government.

The banking and political systems are working “hand in glove” in an attempt to disband nation states.

“Globalists” are trying to engineer a world war as a means to introduce a worldwide government.

Climate change is a “scam” intended to push forward this transnational government.

In the most recent interview, filmed in April last year, Farage said the EU is “the prototype for the new world order”, and “globalists have wanted to have some form of conflict with Russia as an argument for us all to surrender our national sovereignty and give it up to a higher global level”.

In an earlier interview with Jones, who is also banned from Twitter, Farage mentions Bilderberg, saying: “These lunatics genuinely believe that they know what’s best for us, genuinely believe in this concept of global government, and it will be a disaster.”

Later in the same interview, from June 2010, Farage argues Bilderberg members, along with other supposed plotters, could soon start “censoring and maybe ultimately even imprisoning those who challenge them and fight them”.

A spokesman for the Board of Deputies of British Jews said: “It is vital that our politicians distance themselves from conspiracy theories and conspiracy theorists, including those who trade in antisemitic tropes. We would call on Nigel Farage to repudiate these ideas and to commit not to dignify oddball nasties like Alex Jones with his presence again.”

The Community Security Trust, which monitors antisemitic sentiment, said Jones was “a notorious conspiracy theorist who should be beyond the pale for any mainstream politician”.

A spokesman said: “Furthermore, for Jones’s conspiracy-minded audience, Farage’s references to ‘globalists’ and ‘new world order’ will be taken as familiar codewords for antisemitic conspiracy theories.”

A spokesman for the Muslim Council of Britain said Farage’s close links with Jones and Infowars “demonstrates a serious lack of judgment by Mr Farage and a willingness to tolerate Islamophobia”.

The Labour MP David Lammy said the interviews showed “serious questions should be asked about Farage’s associations and networks”.

He added: “His indulgence in conspiracy theories about a ‘new world order’ should send chills down the spine of all who are aware of how these tropes have been used in the past.”

Graham Foulkes, whose 22-year-old son, David, was among 52 people killed by Islamist attackers on 7 July 2005, said he was aghast at Farage’s decision to be interviewed by Jones so many times.

“It fills you with despair that such a high-profile politician could even consider giving people like that the time of day,” he said. “It’s hard to understand. There can be no rational motivation to speak to people who are, shall we say, in need of help.”

Lenny Pozner, whose six-year-old son, Noah, was the youngest of 26 people shot dead at Sandy Hook, has sued Jones for saying the massacre was faked. In a recent legal deposition, Jones said he had argued this because of “psychosis”.

In a statement to the Guardian, Pozner said: “When people hear stories like mine, where conspiracy theorists or purveyors of fake news are destroying an individual or a family, they often feel sympathy or express their shock or horror over the ways that these people are affecting our lives. But many fail to realise that this behaviour doesn’t simply affect me or other victims of mass-casualty events.

“When people in positions of authority or influence consume, perpetrate, and regurgitate conspiracy theories, they legitimise the lie, they normalise the hate, and build policy that affects every citizen on this planet.”

Farage and the Brexit party were contacted for comment.

Jones: “Why is the left allied with radical Islam?”

Farage: “Because they hate Christianity. They deny, absolutely, our Judeo-Christian culture, which if you think about it actually are the roots, completely, of our nations and our civilisation. They deny that. They also want to abolish the nation state – they want to get rid of it. They want to replace it with the globalist project, and the European Union is the prototype for the new world order.”

August 2016

Farage: “If America, as the leader of the western world, once again becomes the leader of the free world, well then I think, basically, we will have done away with the globalists.”

November 2012

Farage: “The fact is that the banking system and politics became hand in glove – one and the same thing. And that’s been a complete disaster. The amazing thing is, we have had elected prime ministers in Greece and Italy removed by the bully boy bureaucrats and replaced by former Goldman Sachs employees. You honestly cannot believe what is going on.”

June 2010

Farage: “You mention yourself the Bilderberg group – these lunatics genuinely believe that they know what’s best for us, genuinely believe in this concept of global government, and it will be a disaster.”

February 2010

Farage: “Yes, it all fits together, doesn’t it? Hand in glove – the big businesses, the bureaucrats, they have the sole right to make laws. It all fits together. They’re all very happy with the world they’re creating.”

December 2009

Farage: “We have a political class across the world that are basically aiming for a form of global governance. If you don’t believe me, look at what’s happening in Copenhagen. Governments are sitting there trying to sign us up to treaties on a very, very questionable concept of global warming caused by C02 emissions.”