Sportaragon.com - a website covering football in Zaragoza’s region - cited a report from The Sun that a deal has been struck between the two clubs.
The website adds that several leading clubs from both England and Spain had been monitoring the winger’s progress, but the Red Devils appear to have won the race for his signature.
Reports label Mejia as a ‘goalscoring wideman’ and is likely to be integrated into United’s youth system. But it could not even be excluded that young star may be aligned in certain matches of first team during next season.