Shakhtar Donetsk president Rinat Akhmetov has confirmed six players have failed to return to Ukraine, reportedly due to safety concerns.
The ongoing political tension between Russia and Ukraine was heightened further last week when a passenger jet crashed on the border of the nations after apparently being shot down.
Shakhtar are currently unable to play in Donetsk because of safety issues - the region is occupied by pro-Russian separatists - and Akhmetov has now confirmed reports that six of the club's players have gone AWOL.
"It is true, six team players have not come - Alex Teixeira, Fred, Dentinho, Douglas Costa, Facundo Ferreyra and Ismaily," Akhmetov told R-Sport.
"I don't rule out that these players will return to the team quickly.
"Players have contracts that they have to abide by. If they do not come, I think, they will be the first to suffer.
"Each of them has a minimum release clause, which is tens of millions of euros. If someone wants to reduce this amount by a million, then such a decision is our right. There won't be a clearance sale."
Akhmetov went on to say that the Ukrainian champions would ensure their players were safe and believes "there is nothing to fear".
"Hopefully, the mind and heart will prevail over misunderstanding, and the players will not follow temptation and fear. Especially since there is nothing to fear," he added.
"We are ready to provide security. We will not take risks and in any case we won't bring players to dangerous places.
"We want to play in Donetsk very much, but, unfortunately, at the moment we cannot do it. We will play where we will be allowed to: we would like to do it in Kharkiv.
"The decision regarding the championship is taken by the Ukrainian Football Federation. Through our game, we will call for peace and try to bring joy to our fans."