Deputy assistant to President Trump Sebastian Gorka participates in a discussion during the Conservative Political Action Conference at the Gaylord National Resort and Convention Center February 24, 2017 in National Harbor, Maryland Alex Wong/Getty Images

A far-right Hungarian group sanctioned in the US for collaborating with Nazi Germany has claimed one of President Donald Trump's national security advisers is one of them.

Kornél Pintér, the leader of the Hungarian group Vitezi Rend, known for its history of anti-Semitism, has said he met with Trump's deputy national security adviser, Sebastian Gorka, and that Gorka "was sworn in" to the group.

Pintér made the claim in an interview with The Forward, an American Jewish newspaper published in New York City.

"I met with him in Sopron [a city near Hungary's border with Austria]. His father introduced him," Pintér told The Forward. "In today's world it is rare to meet anyone as well-bred as Sebastian or his father, Pali," he added. "Of course he was sworn in."

Another high-ranking member of the group named Gyula Soltész also confirmed Gorka's membership to the publication.

The group's founding members who participated in the persecution of Jews and other members of Hungarian society during the Second World War are currently barred from getting a visa to enter the US. The burden falls on current members to prove that they didn't take part in war crimes. Gorka was born in 1970 in London, UK, but would be required to reveal his membership on his visa application.

The name Vitezi Rend translates from Hungarian as the "Order of Heroes". It is one of 12 groups from Hungary that the US has identified for their collaboration with the Nazis. Vitezi Rend was founded by Hungarian leader Miklos Horthy who ruled from the 1920s to 1944 and handed over Jewish Hungarians to Germany. Horthy rewarded Vitezi Rend's members with property stolen from them.

Germany invaded in 1944 and the Final Solution was established against the Jews who were moved into ghettos. Vitezi Rend was outlawed after the Soviet invasion of Hungary in late 1944 and Pintér's group is a reconstitution of the original, calling itself the "Historical Vitezi Rend." Members continue to hold views of racial nativism.

In February, Gorka defended the fact that he wore the group's medal to President Trump's inaugural ball on 20 January and during television interviews, saying it reminded him of his father who fled Communism and was awarded the medal by Vitezi Rend in 1979.

Gorka has been linked to Hungary's right-wing movement for years. After growing up in London, he settled in Hungary and went to school for a Masters degree in international relations and diplomacy at Corvinus University in the early 1990s. He later gained a PhD from the same university.

In 2007, as a director of his own Institute for Developing Democracy, Gorka announced he would lead a splinter group to break off from the right-wing Hungarian Fidesz party led by Hungary's current Prime Minister Viktor Orban.

Within Europe, Orban has been one of the few elected leaders to provide a rallying cry for European nationalists like France's Marine Le Pen. He has called immigrants "poison", warned of a "parallel Muslim society", and condemned policies that help refugees.

After arriving in America in 2008 Gorka became a Fox News contributor and served as the national security editor at the right-wing news website Breitbart, which Trump's chief strategist Steve Bannon headed until joining Trump's election campaign.

Gorka has drawn criticism as one of Trump's counterterrorism experts for singling out Islam as the root of terrorism and his claims that the current War on Terror is a war "for the heart of Islam".

The White House did not respond to a request for confirmation about whether Gorka revealed that he is a member of Vitezi Rend on his visa application or whether he has, in fact, taken an oath to the group.