JJ Gabriel, the 15-year-old prodigy nicknamed ‘Kid Messi’, has unexpectedly asked to quit Manchester United.

In a move that has left United shocked and is almost unprecedented, Gabriel – whose full name is Joseph Junior Andreou Gabriel – has sent formal notice that he wishes to cancel his registration at the club with immediate effect to become a free agent.

It is understood that Gabriel — whose father Joe O’Cearuill won two senior caps for Ireland — is not in line to immediately join another club, but has decided he wants to leave United – the club he has played for since the age of 11.

Clubs cannot sign players to professional contracts until the age of 17 or scholarship agreements until they turn 16, which Gabriel does not do until October 6. United can challenge Gabriel’s request to cancel his registration.

Premier League rules state that: “During your child’s registration period, their registration may only be cancelled if everyone agrees (the club, player and their parent/carer).”

The rules add: “If the parties don’t agree, then any person involved can also ask the Premier League to provide a binding decision on a termination request.”

It remains to be seen whether United refuse Gabriel’s request, but the club are not thought to see the situation as irretrievable yet and have not given up hope of rectifying it. United had planned to include the youngster in the first-team squad for Wednesday night’s Carabao Cup tie against Brighton.

News of Gabriel’s desire to leave is a surprising development and raises serious questions about the running of United, who have traditionally been English football’s most successful talent factory.

Gabriel’s request to cancel his registration could not come at a worse time for United co-owners Jim Ratcliffe and the Glazers, following the Manchester derby defeat by 10-man City and large-scale fan protests against them.

Just last week, Gabriel shot to prominence outside Old Trafford by scoring a hat-trick against Sabah in the Uefa Youth League, having last season become the youngest winner of United’s Jimmy Murphy young-player-of-the-year award.

Ryan Giggs, a former winner of the Jimmy Murphy award himself, described Gabriel as a “generational talent” and likened his development to that of Wayne Rooney.

Gabriel has been nicknamed ‘Kid Messi’ after going viral on social media and a source at one of United’s rivals told the Daily Telegraph: “This would be like Barcelona losing Messi before he had played for them. It would be huge.”

Gabriel’s social media accounts were wiped of all mention of United the day after his hat-trick against Sabah and the club were informed this week that he no longer wishes to play for them.

Manchester City tried to snatch Gabriel away from United last year and the teenager has also been linked with Arsenal, Real Madrid and Bayern Munich.

Gabriel scored more than 20 goals for United’s under-18 team last season and had been expected to make his first-team debut for the club this term.