Real Madrid among clubs pursuing Man United academy forward JJ Gabriel, 15

Real Madrid are among the clubs seeking to sign Manchester United academy forward JJ Gabriel after the 15-year-old informed United earlier this week that he wants to leave and submitted formal notice to cancel his registration; the club can contest that request.

Sources say Barcelona, PSG and Bayern Munich also have firm interest in Gabriel and that Real Madrid's pursuit is particularly strong, with the Spanish club aiming to bring him in immediately and place him with Real Madrid Castilla. Castilla compete in senior football in the regionalised third tier of the Spanish system. Last season Castilla were coached by Alvaro Arbeloa, who then took over the senior Real side following Xabi Alonso's dismissal and has since moved to Fulham, while Thiago Pitarch, who was 18 at the start of last season, featured for Castilla in a Premier League International Cup match against Southampton in October and made 16 senior appearances across the campaign.

People close to Gabriel, who turns 16 on 6 October, say they feel let down by Manchester United and allege promises about a pathway to the first team have not been fulfilled. United counter that it had been anticipated Gabriel would become the club's youngest ever senior player by participating in Wednesday night's EFL Cup tie with Brighton; given United lost 3-2 after leading 2-0, the club accept it is debatable whether that would have occurred.

Manchester United have not abandoned efforts to retain Gabriel but say they do not fully understand his reasons for wanting to leave; it is understood the player is not currently training with the club. United also state Gabriel's registration runs until the end of the season, which the club say would make any departure easier at that point when he will be 16.

Speaking after the Brighton game, head coach Michael Carrick, who handed Gabriel his senior debut during the pre-season match against Atletico Madrid in Stockholm, warned of the need for caution: "I just think we've got to be really careful of the whole situation," he said. "He's a young boy. He's 15, and for me, definitely, and from a club point of view, looking after our younger players - their welfare, their well-being, their exposure - we've got to be really conscious of that in this situation."

Sources close to Gabriel have rejected concerns about his age and physicality and pointed to examples such as Max Dowman, who made his Arsenal debut at 15 last season, as evidence of other clubs' willingness to trust younger players. Chelsea are also reported to have a major interest in the teenager.

Any immediate transfer is complicated by rules on registering young players, but Gabriel's EU passport means it is possible he could join a club within European Union borders on his 16th birthday; otherwise United say his registration would allow a move once the season ends.