The Hearts first team squad and PFA Scotland have submitted a formal complaint to the Scottish Premier League over unpaid wages at Tynecastle.
Action has been taken after payment of the players' salaries for December failed to arrive on time.
This is the third successive month in which players have gone unpaid. The players' union PFA Scotland is now acting for the Hearts squad as they take their fight to the authorities.
The SPL confirmed receipt of the letter in a statement released on Friday.
"The SPL received a letter from PFA Scotland this afternoon on behalf of several PFA members," the statement read.
"This letter will be considered by the SPL board at its meeting on Monday. No further comment will be issued at this time."
Club owner Vladimir Romanov is reportedly looking to sell his stake in the club.