Image copyright Reuters Image caption BTS, speaking here at the UN, are the world's biggest K-pop band

The management of K-pop stars BTS have apologised after a photo emerged of a band member wearing a hat with a badge resembling Nazi insignia.

It comes immediately after a furore over a different band member wearing a T-shirt with a picture of an atomic bomb on it.

Bit Hit Entertainment said both incidents were "in no way intentional" and not the fault of the band members.

BTS have a huge following online and many fans consider them role models.

"We would like to offer our sincere apologies for inadvertently inflicting pain and distress to anyone affected by totalitarian regimes in the past... [and] those affected by the use of atomic weapons," said Big Hit Entertainment, the agency representing the band.

BTS are arguably the world's most popular K-pop group. Thousands had criticised them for the fashion faux pas, though many more fans defended the group's actions.

'Denigrating the memory of the past'

In October, social media users began sharing a picture of band member Jimin wearing a shirt depicting the US atomic bombing of Japan and a Korean liberation slogan.

Image copyright Ourhistory/Screenshot

It's unclear when the photo was taken, but that did not stop it from going massively viral - leading Japanese channel TV Asahi to cancel an appearance by the group.

At the time BTS issued a statement saying they were sorry to miss the performance, but not addressing the T-shirt.

Social media went on to find old photos of band member RM wearing a hat bearing what looked like a Nazi symbol.

The photos started to go viral, prompting criticism by the Jewish human rights group the Simon Wiesenthal Centre, which said the symbol depicted on the hats were of the Nazi SS Death Head logo.

"It is clear that those designing and promoting this group's career are too comfortable with denigrating the memory of the past... the management should publicly apologise," said Rabbi Abraham Cooper, a director at the Simon Wiesenthal Centre.

Big Hit told the centre that the hat which had caused offence had been given to the singer to wear by a stylist at a magazine photo shoot in 2014.

In its lengthy Facebook apology, Big Hit Entertainment stressed that it "does not support any organizations or groups oriented towards political extremism and totalitarian beliefs including Nazism" and that the band were "in no way responsible for any of the issues outlined".

Image copyright Reuters Image caption Leaflets denouncing BTS which showed Jimin in the controversial shirt were distributed outside their concert venue in Japan

The agency said it had contacted associations in Japan and Korea that represented victims affected by the atomic bombs, and that it had also delivered a letter to the Simon Wiesenthal Centre.

The centre said it "welcomed an apology" from the group, adding that they were "reaching out to BTS to urge they harness their international fame to celebrate the good not serve the forces of evil."