Rinat Akhmetov, the billionaire owner of football club Shakthar Donetsk, has threatened action against an Argentine and five Brazilian players for refusing to travel to eastern Ukraine over concern about the recent conflict and the Malaysia Airlines flight crash.

As the Super Cup tournament is set to begin on 22 July, the six players had declined to travel to the strife-torn region, missing the team's Geneva flight to Lviv. The players are in France after finishing their exhibition game against Olympique Lyon.

Confirming the players' refusal in the club's website, Akhmetov said: "It is true, six team players have not come. I don't rule out that these players will return to the team quickly, and some of them tomorrow. 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."

The team's hometown of Donetsk is embroiled in bloody conflict as most of the territories are under the control of pro-Russian rebels, from whom the Ukrainian government forces are battling to retake the area.

Akhmetov has said if Donetsk is unsafe for the matches, other places can also be considered as a venue.

The six players are Brazil's Alex Teixeira, Fred, Dentinho, Douglas Costa, Ismaily and Argentina's Facundo Ferreyra. The combined value of the players is about €57m (£45m), according to transfermarkt.com.

All the players are strong contributors and their absence will be felt enormously in the Ukrainian league. Speculation has also emerged about foreign clubs looking to poach these players or their exit having a domino effect on others in the team.

Meanwhile, the team's coach Mircea Lucescu has accused "agents" for the players' disappearance.