The International Ice Hockey Federation has suspended six players from international play, including newly acquired Jason Krog of the Vancouver Canucks.
The IIHF also suspended Russians Alexander Radulov, Nikita Filatov, Viktor Tikhonov and Fedor Fedorov, as well as Tomas Mojzis of Czech Republic.
At issue are claims each player is under contract with both Russian and NHL clubs. The NHL and the newly reconstituted Russian league, called the Continental Hockey League, have agreed to respect existing contracts although no formal deal has been signed.
"We hope that this can be resolved amicably and in a timely manner," IIHF president Rene Fasel said Friday. "It is unfortunate that we are already facing such difficulties after the progress that was made last week.
"I am hoping that all sides can come to a solution."
Fasel has requested paperwork from all affected clubs before July 31 to further investigate.
Radulov's signing with Salavat Yulaev Ufa of the KHL last week made the biggest waves. Radulov said he had signed a lucrative deal with the club, but still has one year remaining on an entry-level contract with the Nashville Predators.
The NHL and Predators quickly released statements re-asserting Nashville's rights.
Krog, one of the top scorers in the American Hockey League last season, signed with Vancouver in mid-July after exploring the possibility of playing in Russia.
Filatov and Tikhonov, the grandson of the legendary Russian coach of the same name, were each drafted in the first round of the NHL entry draft in June. They subsequently signed with Columbus and Phoenix, respectively, with their Russian teams alleging they still own the players' rights.
Mojzis played in Russia last season and recently signed with the Minnesota Wild.