Mohun Bagan on Thursday wrote a 255-page letter to football's world governing body FIFA, challenging the interim relief to India captain Bhaichung Bhutia.
The letter, addressed to FIFA general secretary Jerome Valcke, detailed the reasons for Bhutia's showcause and the consequent six months' without-pay suspension from the Kolkata club, Mohun Bagan general secretary Anjan Mitra said.
"We want FIFA to intervene into the matter. Bhutia has a valid contract with us for the ongoing 2009-10 season, yet he has signed for another club (East Bengal). Bhutia has violated clauses eight, 10 and 19 of the two-year contract. We demand justice from the FIFA," Mitra told PTI.
Bhutia earlier signed up for East Bengal after getting an interim relief from All India Football Federation-appointed arbitrator Amarendra Sharan on September 25.
Mohun Bagan has also forwarded the document to the Indian Football Association (IFA) and Bhutia.
IFA Secretary Utpal Ganguli confirmed the receipt of the letter.
"Let them do whatever they think is right, I have nothing to comment. I am fighting to be fit for our next match (against Shillong Lajong FC on November 12)," Bhutia told a website.
Bhutia was suspended for six months without pay by Mohun Bagan on June 8 for missing a few team training sessions and an exhibition match.
He appealed to the IFA but later the AIFF took up the matter. The IFA's Players' Status Committee, however, failed to decide on the matter as one member refused to give his opinion.
The AIFF then asked its outgoing General Secretary Alberto Colaco to mediate between Mohun Bagan and Bhutia.
After Colaco could not find a solution, AIFF Executive Committee in its meeting on August 30 had decided to refer the matter to an arbitrator.
