July 16 (Reuters) - Serie A club Spezia have been banned from four transfer windows, starting in January next year, after breaching FIFA rules on signing minors, world soccer"s governing body said on Friday. Spezia, who competed in the Italian top flight for the first time last season, were also fined 500,000 Swiss francs ($543,832) for the offence, which involved signing minors from Nigeria. "The FIFA Disciplinary Committee found that Spezia Calcio had breached article 19 of the FIFA Regulations on the Status and Transfer of Players (RSTP) by bringing several Nigerian minors into Italy using a scheme aimed at circumventing the aforesaid RSTP article as well as national immigration law," a FIFA statement read. "The protection of minors is a key objective of the regulatory framework governing the football transfer system." Former Barcelona midfielder Thiago Motta was appointed Spezia manager last week, while the club were bought by U.S. investors in February. They said they would appeal the decision. "We are surprised by FIFA"s decision to impose this heavy transfer ban," Spezia president Philip Raymond Platek Junior said in a statement on Friday. "The new ownership had no role in the alleged transgressions. We will appeal and take appropriate measures to ensure that our team remains competitive in the years to come." International transfers are only permitted if the player is over the age of 18, unless one of the following criteria are met: * The player"s parents move for non-football-related reasons. * The transfer takes place within the European Union (EU) or European Economic Area (EEA) and the player is over 16. * The player lives no more than 50 kilometres from the border and the club is no more than 50km from the border. * The player flees his country of origin for humanitarian reasons. * The player is a student and moves without his parents to another country temporarily for academic reasons in order to undertake an exchange programme. It is unclear how many Nigerian players Spezia signed, but the alleged irregularities occurred between 2013 and 2018. It is not the first time FIFA has issued such a ban. In 2019, FIFA banned Chelsea from two transfer windows after the Premier League club were found to have breached article 19 in the case of 29 minor players. ($1 = 0.9194 Swiss francs)