Bayern Munich are refusing to allow Robert Lewandowski and David Alaba to join up with their respective countries for games in the UK over the international break.
Under the current strict coronavirus protocols in place in Germany, Bundesliga and Bundesliga 2 players would have to quarantine for 14 days upon returning from a "mutation zone" nation.
Poland are due to play England at Wembley on March 31, while Austria will face Scotland at Hampden Park on March 25.
"If it remains the case that the returnees from England have to go into quarantine, we will not be able to put Lewandowski down," Bayern sporting director Hasan Salihamidzic said to German news agency Sport-Informations-Dienst.
When questioned about it during his press conference on Friday, Hansi Flick confirmed: "We will not agree. If something changes, though, we'll support that."
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However, Lewandowski will be available for Poland's games with Hungary and Andorra because those countries are not on the German government's "mutation zone" list, while Alaba will be available for Austria's games at home to the Faroe Islands and Denmark.
Scotland will already face a weakened Austria side due to the fact that several regular players in Austria's squad are based in the German top flight.
Because of the mandatory quarantine period, if Lewandowski and Alaba were allowed to travel to the UK they would miss Bayern's clash with RB Leipzig on April 3, both legs of the Champions League quarter-final with PSG (April 6 and April 12) and the game with Union Berlin on April 10.