Elements of Asian communities in Britain are racist towards black people, prominent Asians have warned, after a 14-year-old boy of Pakistani origin from Bradford was convicted of stabbing his black teacher in a racist attack.

Nihal Arthanayake, a BBC DJ and presenter, said it was necessary for British Asians to have a “very uncomfortable conversation” about whether “Asians are being brought up to be racist towards black people”.

He said: “I think that there has traditionally been an issue with darker skin being seen as unattractive and people who have dark skin as inferior, and if that is applied within the Asian community how could that attitude not also apply to people of African heritage?”

He was commenting after a judge in Bradford sentenced a boy to 11 years for stabbing supply teacher Vincent Uzomah, a 50-year-old of Nigerian origin, after calling him the N-word.

Though the judge, Jonathan Durham Hall QC, banned reporting of the boy’s name, he allowed the media to refer to his ethnicity, suggesting it was relevant to the case. He told the boy he was a “dangerous young offender” and an “antisocial bully” who hated being disciplined by a black man. “You would not tolerate being told off by this gentleman of this background,” he told him.

Arthanayake, who grew up in Essex but is of Sri Lankan descent, held a phone-in on his BBC Asian Network show on Tuesday in which he invited listeners to share their views and experiences. One man, who gave his name as Sanjay from Leicester, phoned in to suggest it was scientifically proven that black people were less intelligent than non-blacks – a comment robustly challenged by Arthanayake, who pointed out that the most powerful man in the world, Barack Obama, was black. One woman, Kavaita from the Midlands, recalled being told by her parents aged 12 that she wasn’t allowed to be friends with a black girl in school.

Another of his callers was Gohar Almass Khan, from the South Leeds Community Alliance, a community group. “We need to be honest: generally people from the Indian subcontinent – Indian, Pakistani, Bangladeshi, Sri Lankan – are more racist towards black than white communities. This is a fact,” he said.

Khan said it was “quite deep-rooted in our psyche” and stemmed from the Hindu caste system, which favours the largely lighter-skinned Brahmins over the darker Dalits, or untouchables. “Even in your own household when the kids are born, the kids that are light-skinned, light-haired are thought to be more beautiful and favoured by the parents compared to the darker,” he said, suggesting that the solution to the problem was for Asian communities to “get out of their ghettos”.

Mohammad Shabbir, a Labour councillor in Bradford, said: “There is cultural racism towards black people.” He noted that indigenous black Muslims known as Siddis, whose ancestors were brought to the Indian subcontinent as slaves, were often the subject of racism and discrimination. Also, he said, “there is a legacy or colonial rule and a cultural inferiority and so people see the world through colonial eyes, which basically means white is good”.

He added: “However, within the context of the UK I would say that this is prejudice rather than racism. From a faith perspective there is no racism. However, culture and faith boundaries get confused. Personally I’m politically black and a proud and inclusive Muslim working towards unity of our city.”

But Alyas Karmani, an imam, youth worker and councillor in Bradford, said that while there was prejudice and discrimination against black people by some Asians in the city, largely there was a healthy co-existence between the communities, which he witnessed in the mosques.

He warned against extrapolating from one isolated incident, saying that young Pakistani men were already demonised as terrorists, groomers and gangsters without being tarred with the racism brush. “There has been this problematising of young men in Bradford in particular ever since the 2001 riots,” he said.

Karmani suggested the boy who stabbed his teacher was probably motivated by the “thug mentality”, a desire to gain respect whether on social media or in real life, which stems from a feeling of powerlessness. “It’s the powerless taking potshots against the powerless. Real racism is power, to selectively advocate for one group in preference to the other, which doesn’t apply here. Really it seems much more like what Edward Said called the clash not of civilisations but of ignorance,” he said.

Bradford, West Yorkshire. Alyas Karmani, a local imam, said there was a healthy co-existence between Asians and black people in the city. Photograph: Christopher Furlong/Getty Images

This is separate from the subtle snobbery ingrained in British Asian communities as a hangover from the caste system, said Karmani. “It’s rooted in the caste system, which institutionalises racism and breeds the idea that just because you are born into a certain family you are better than others. It’s also an issue of pigmentation. To be pale still carries elevated status in many families. It’s ingrained in the Asian concept of attractivity: that black is ugly and pale is beautiful.”

He added: “It’s far more complex when you explore the range of prejudice based on caste, biraderi [clans] and region. Caste discrimination is massive in the UK and never spoken about.”

Khalid Mahmood, the Labour MP for Birmingham Perry Barr, rejected the idea that the boy who stabbed his teacher had been primarily motivated by racism. He too felt it was more about gang culture, where the N-word was used simply to signal inferiority. “That word, as well as ‘coolie’ [a derogatory word used to describe Asian labourers] is used in a derisory sense to indicate that someone is lesser than you,” he said.

Mahmood said that what he sometimes witnessed in the Asian community was not so much racism but internal snobbery, which motivated men in particular to try to stop their women from getting involved with black men or men from other castes or religions: “You see it in these men, they feel they are losing grip of their women.”