On Thursday, Bellingham posted a screengrab of the now-deleted message on Twitter which called him an “overrated talent” and said “Black people only think about money.”
Inspector Lee Page said officers are “thoroughly investigating these abhorrent comments” and added that the police had contacted the victim and the victim’s family.
Though the user has deleted the tweet and deactivated the account, Twitter has taken action on the account as it violated the company’s Hateful Conduct Policy.
A Twitter spokesperson told CNN that during the current football season in the UK, the company had suspended nearly 300 accounts and “taken action” on nearly 6,000 examples of abuse and hateful content.
“We are continuing to proactively engage and collaborate with our valued partners in football to identify ways to tackle this issue collectively,” the spokesperson said.
Midfielder Bellingham signed for Dortmund on Monday for a fee widely reported to be more than $26 million. He played his final game with his boyhood club, Birmingham City, on Wednesday and was visibly emotional at the final whistle.
Dortmund said in a statement to CNN that the club “strongly support and stand with” Bellingham.
“There is absolutely no room for racism and all forms of discrimination at Borussia Dortmund,” the statement read.
Watford player Kabasele said he received numerous abusive posts on his personal social media accounts and urged platforms to do more in tackling the issue. Neither Twitter or Instagram replied to CNN’s request for comment at time of publication.
Bellingham is the latest talented English youngster to opt to develop his career in the Bundesliga, following in the path of Jadon Sancho who quickly became an England international after joining Dortmund from Manchester City in 2017.