Chelsea’s transfer ban was caused by Ivory Coast-born star teenage footballer Thierno Ballo after German Magazine Der Spiegel leaked information.

The Blues broke FIFA transfer rules by paying a 14-year-old midfielder and then “parked” him with another club until he was legally allowed to sign for themAccording to Der Spiegel claims that Chelsea reached an agreement with Ballo, now 17, in breach of regulations, paying him £10,000 in 2016 with a promise of £215,000 per year from this summer as well as up to £550,000 in bonuses which is against world governing body regulations prohibit EU clubs signing players or offering them incentives until they are in the year they turn 16.Ballo’s mother signed an agreement with Chelsea when the striker was 14 and registered to Bayer Leverkusen and he then moved to German fourth-tier club Viktoria Koln “in preparation” for a trip to Cobham Training Centre designed to focus his development ahead of his eventual move, which happened in January. The Europa Champions were handed a two-window ban by FIFA for breaching rules over the signing of young players but Frank Lampard side are hoping to appeal the rap so they can sign players in January.Ballo is an Austrian Under-17s international, who scored 10 goals for Chelsea’s youth teams last season.