The decision comes days after CAS overturned the IIHF's 2022 ban on Russia, prompting ice hockey's governing body to begin exploring ways to implement the ruling despite significant logistical and sporting challenges.
The IIHF has previously said participation by Russia and Belarus would be assessed on a tournament-by-tournament basis. On Saturday, however, it confirmed that Belarus would not take part in the 2027 World Junior Championship in Canada or the 2027 men's World Championship in Germany.
"The Federation intends to protect the rights of Belarusian hockey and will soon determine specific legal steps, including the possibility of appealing to the Court of Arbitration for Sport regarding decisions of the IIHF bodies," the Belarus federation said in a statement.
While maintaining its opposition to the CAS ruling on Russia, the IIHF said it was reviewing how to comply with the decision and had begun exploring options for Russian participation in future championships.
"The IIHF must work within the applicable framework while upholding its responsibility to preserve international competition and protect the sport as a whole," the governing body said in a statement.
"The IIHF is therefore exploring all available avenues, including opening discussions with all affected MNAs (national associations), including the Russian Ice Hockey Federation, to identify a constructive way forward that serves the interests of global ice hockey."
Belarus federation chairman Alexander Bogdanovich questioned why the IIHF was prepared to examine changes required to accommodate Russia while excluding Belarus.
"The decision essentially replicates the outcome of the previous cancellation: Belarusian teams are once again excluded from the tournament, with only the rationale changing," Bogdanovich said.
"The inconsistency of the approach also raises questions."
Russia and Belarus have been excluded from IIHF competitions since Moscow's invasion of Ukraine in February 2022, with Belarus sanctioned for its support of Moscow's war effort.
Norway, Denmark, Sweden, Finland, Latvia and the Czech Republic have refused to play Russia, while Canada has barred Russian and Belarusian teams from participating in the World Junior Championship in Alberta.