Six of Poland’s 23 swimmers are reportedly unable to compete at the 2020 Tokyo Olympics due to an administrative error by the country’s swimming federation.

Swimmers Alicja Tchórz, Bartosz Piszczorowicz, Aleksandra Polańska, Mateusz Chowaniec, Dominika Kossakowska and Jan Holub were already in Japan when they were informed that a misunderstanding of FINA’s qualifying standards meant they were ineligible to compete in the 2020 Olympic Games. FINA is an international organization that sets the standards for competitions in various aquatic sports.

In a statement, Polish Swimming Federation president Pawel Slominski expressed, “great regret, sadness and bitterness about the situation related to the qualification of ours players for the Olympic Games in Tokyo.”

This error cuts Poland’s Olympic swim team down from 23 athletes to 17. Tchorz was set to be a 3-time Olympian, having competed in both 2012 and 2016. The six athletes have already returned to Poland and are reportedly seeking legal action and a reorganization of the country’s swimming federation board.