Mohammed Waheed, who coaches Alpha United Juniors, said players as young as seven had been subjected to racial slurs and threats of violence.

He wrote to Kensington Palace claiming he had raised the issue with the Football Association (FA) to no avail.

Prince William said all those responsible must be held to account.

The prince, who is president of the FA, said he was "particularly saddened" to hear about "the effects this intolerable action can have on those who are simply wanting to play a game of football".

Mr Waheed said he decided to publicise Prince William's letter because he felt the FA had not acted quickly enough

A letter to Mr Waheed from Prince William's private secretary said the royal had raised Mr Waheed's concerns with the FA and asked them to "take the necessary action".

The prince also expressed his "sincere sorrow to anyone affected" and "profound support for all that you and the club are doing to stop racism".

Mr Waheed wrote to him in January and decided to share his response, which was sent last month, as he was unhappy with West Riding FA's investigation process.

Mr Waheed, who founded the club, said the same abuse happens "over and over again"

He said Alpha United Juniors had reported "between 50 and 60 cases" of racism.

Player and coach Ateeb Hussain, 17, told the BBC he had been racially abused "a lot" by opposition footballers, coaches and spectators.

He said he felt "very uncomfortable with the words that are coming out of their mouths".

Ateeb Hussain said he had suffered a lot of racial abuse by opposition clubs

Mr Waheed, who also founded the club, said: "The same transgressions happen over and over again with no accountability taken from the county FA.

"We've had many clubs reach out saying the exact same thing, so clearly there's a failure somewhere along the line."

The West Riding County FA said it condemned "any form of discrimination, whether in football or out of it, and where it sits within our jurisdiction, we will do all we can to bring perpetrators to account".

A spokesperson added: "We have received two referrals from Alpha this year, both of which are being investigated."