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KSI explains why he quit the Sidemen

KSI smiles while wearing a black bandana and t-shirt Getty Images

"This decision is completely my own," he said.

Social media star and Britain's Got Talent judge KSI has explained why he is leaving the YouTube group Sidemen after 13 years.

KSI, whose real name is Olajide Olatunji, has made football, comedy and challenge videos with the group since 2013.

In a video on YouTube, KSI said he "was being pulled in a lot of directions than ever before" but he'd "gone back and forth on this decision for a very long time" before finally making this choice.

Sidemen said his decision "came as a surprise" but they wished him well for the future.

KSI, Vikram Singh Barn, Ethan Payne, Harry Lewis, Joshua Bradley, TBJZL and Simon Minter inside a shop - Lots of fans are seen in the background, filming on their phones from outside the store.Getty Images

The collective have more than 140 million YouTube subscribers between them

KSI added that "nothing bad has happened" between him and the group: "This decision is completely my own," he said.

"Between everything else in my life, I feel like I've been running at full speed, at 100mph."

In a statement posted on social media by Sidemen, the group said they were "sad to share the news" that KSI had "decided not to continue".

"We had an amazing time on this journey with him and we wish him all the best with his future endeavours," they said.

KSI in front of a BGT banner with arms outstretchedGetty Images

KSI has lots of other jobs including BGT judge

The news came after KSI appeared in Saturday's final of the ITV show Britain's Got Talent.

He started making videos in 2008 and became well-known as an online streamer. He has more than 18m subscribers to his personal YouTube channel, and co-founded Prime hydration drinks .

He is also a musician, former boxer and recently bought a stake in Dagenham & Redbridge Football Club.

Earlier this May, his team Prime FC won the Baller League UK season 3 championship, a six-a-side football competition featuring influencers, celebrities, and former professional players.

Sidemen have more than 140 million YouTube subscribers between them, with KSI the most famous member of the group.