FC Sion say they have filed a criminal complaint against members of FIFA's executive committee over its threat to suspend Switzerland from world football.
The club said on their official website that the threat, made on 17th December, amounts to blackmail and a breach of basic legal rules.
FIFA wants the Swiss national association to discipline Sion within one month in a long-running legal battle.
Sion are contesting their expulsion from the Europa League in September for fielding players signed during a transfer ban imposed by FIFA in 2009.
If the suspension of Switzerland takes effect, Basel would be prevented from playing Bayern Munch in the last 16 of the UEFA Champions League.
In a statement released on their official website, the Swiss club said: "FC Sion has now filed a criminal complaint against executive members of the committee of FIFA after the threat to exclude the Helvetic Federation and clubs affiliated to it.
"The complaint was sent to the prosecutor in Zurich. It is directed against anyone who participated or contributed to the decision of the FIFA."
The Swiss club were put under a transfer embargo over the signing of Egyptian goalkeeper Essam El Hadary, but proceeded to sign six players in the summer.
Sion then fielded five of the six players during the Europa League play-off tie against Celtic earlier this year and were kicked out of the competition as a result, with UEFA's decision to expel them upheld by the Court of Arbitration for Sport.
FIFA said that they had "taken note of the situation" but said they would not comment until the January deadline for the Swiss Football Association to act had passed.