In May, the Premier League fined City £300,000 and banned them from signing academy players for two years.Fifa has stringent rules in place for signing players under the age of 18 to prevent exploitation and trafficking.
City are adamant they have done nothing wrong, while Chelsea insist they "comply with all Fifa statutes and regulations when recruiting players".
In January last year both Real Madrid and city rivals Atletico were banned from signing players for two transfer windows after breaching Fifa rules relating to the signing of minors.