UFC middleweight champion Israel Adesanya has opened up about facing racism in New Zealand.

The Nigerian-born, Auckland-based fighter, who will defend his belt at UFC 253 against Brazillian Paolo Costa this Sunday, said he was bullied when he first came to New Zealand.

"I really didn't realise me being black was a problem, until I got to New Zealand," Adesanya said in a wide-ranging interview with the Daily Telegraph.

"I'm like, 'Why are you being mean to me, why can't you be kind?'

"My first week in school, there was a kid who was being a dick to me, he lived down the road, he kept riding by my house with his friend telling me, 'Go back to your own country black'.

"I didn't understand it. It was so foreign. I didn't even know this guy, why was he being so mean to me?"

Adesanya said he ended up getting in a fight with the kid, adding that he still "can't fathom" having that kind of hatred.

"That next week at school, he came up to me after interval and pushed me to the ground, and I lost my s---.

"I beat him up, from D block to K block, I beat him up for about a minute and a half, and I was crying while I was whooping his ass, then I ran away and went to hide. It was a pretty traumatic experience for myself.

"I just didn't understand, why are you being mean to me because of the colour of my skin? I still can't fathom it because I'm not of that creed."

Adesanya's comments echoed the speech he made at a Black Lives Matter rally in Auckland in June, where he spoke about his heartbreak of seeing black people being killed by police in America while also touching on the racism he still faces in New Zealand.

The 31-year-old urged people to take action on racial and social injustices, which he says must go beyond merely spreading awareness.

"What the f***, are you stuck in 1942? It's like people's sexual orientation, or their religion, everybody is just fighting each other," he told the Daily Telegraph.

"I don't think people realise that the powers that be want us to be divided because that way we don't focus on the real problem, which is the powers that be perpetrating evils in this world.

"When the march happened, I spoke out and am really proud of what I said, I was really angry and I reacted, but it hasn't stopped yet.

"Reporters asked me this week, 'Like Tyron Woodley [who lost to fervent Donald Trump supporter Colby Covington last weekend] did, are you trying to bring awareness?' What is there to bring awareness to? We all know what's f***ing happening.

"Like Jay Z said, 'I'm past kneeling'. There's no point in bringing awareness no more, what we need is for the world to change, talk to the lawmakers, the councilmen, the mayors, your own city, your own town, your own city, and demand change from whatever you feel is wrong.

"I'm doing my best to make change in my own world. I can't change the world, but I can change the world around me, and I think people should try to do that because it's a shame to see what's happening to black people all around the world."

However, Adesanya says he doesn't see himself as an activist, but merely a "regular dude" trying to get by and do what he loves.

"I'm still human, I'm me and I'm still figuring out my own self.

"I feel like people look at me from a political view. I'm like 'Bro, I'm not the person to be looking at for political takes'. I'm a fighter who has something to say because of what's happening in the world, but I'm not your councilman.

"Go to those legislators and leaders in your town, to get your point across.

"I'm just a regular dude doing extra regular s***. And I'm doing it very well.

"But I'm still the dude who walks around bare foot in west Auckland, walking his dogs through the mud.

"I'm still that guy with his headphones on at Pak 'n Save trying to get my shopping done without having 20 people asking for photos."

Meanwhile, the unbeaten champ also doubled down on his comments claiming he is "bigger than the All Blacks".

"I wasn't lying, and it is not just because of my social media following, I was talking about – he did the same thing I think you're doing, he asked me a question and the media outlets took at as me saying I'm bigger than the All Blacks," Adesanya said.

"You ask me a question, I answer it bluntly. I didn't cop a lot of grief, but you can't argue with me.

"I even said in my answer, I'm not talking about in New Zealand, I have a footprint bigger than the All Blacks, not in New Zealand, but worldwide people know me a lot, and it's just something people have to take, because it's fact.

"If not's a fact to you, that's cool, I don't care what people think."