Following the Russian invasion of Ukraine, FIFA declared that foreign players who have left Ukraine or Russia and do not wish to return would have the right to unilaterally suspend their employment contracts.

The rule, included in Annex 7 of FIFA's regulations on the status and transfer of players, was due to expire on June 30 but football's world governing body has now extended it to the same date next year.

Shakhtar said that some of its international players had left the club on free transfers when ordinarily they would have been sold. 

It said "over-reaching measures" by FIFA had led to "massive loss of player transfer income and a depletion of essential club revenues".

The club and a group of Russian teams attempted to challenge Annex 7 at the Court of Arbitration for Sport but their effort was rejected.

An appeal has now been lodged with the European Commission and Shakhtar is preparing a case at the Swiss Federal Tribunal.

"FC Shakhtar is aware of the decision made by FIFA to extend Annex 7 to the regulations on the status and transfer of players until June 30, 2024," a club statement said. 

"We have taken note of some minor regulatory amendments, but it still unilaterally allows the suspension of international player and coaching employment contracts with Ukrainian clubs without consultation and agreement. 

"This provision is the focus of the ongoing legal dispute between FC Shakhtar Donetsk and FIFA - and its extension means the club stands to lose up to €80 million (£88 million/$84 million) in possible transfer fees, including €40 million (£34 million/$42 million) lost last year.

"Over the past month, FC Shakhtar has been in consultations with the European Club Association (ECA), who has acted as an intermediary between the club and FIFA in order to negotiate possible changes that would protect Ukrainian clubs from further financial losses. 

"Unfortunately, several proposals made by FC Shakhtar via the ECA regarding possible amendments to the regulations were turned down by FIFA."

The ruling does not apply to players and coaches who decided to "arrive in, return to or not leave" either Ukraine or Russia.

Anyone who signed for a club in either country after March 7 last year is also excluded.

The extension was agreed following discussions with UEFA, the ECA, players' organisation FIFPro and the World Leagues Forum.

A FIFA statement revealed that the decision was unanimously approved at a Council meeting led by President Gianni Infantino, which included the leaders of all the continental confederations.

"We believe the extension of annex 7 continues to place clubs like FC Shakhtar in Ukraine in a seriously disadvantaged position with zero protection and threatens our very existence," the club added.

"FC Shakhtar will continue its legal battle with FIFA. 

"The club has already submitted a complaint to the European Commission and is preparing an appeal to the Swiss Federal Court.

"We still count on the ongoing consultation between the ECA and FIFA to develop a financial solution which compensates the losses of FC Shakhtar and other Ukrainian clubs. 

"We hope that a positive outcome can be reached which will be fair and helps us recover at least some of the €80 million we stand to lose as part of the process."

Shakhtar Donetsk won the UEFA Cup in 2009 and has claimed the Ukrainian Premier League title 13 times.

The team has been forced out of its home city due to the war in Donbass which began in 2014, and has played in Lviv, Kharkiv and Kyiv instead.