The Rugby Football League (RFL) intends to support its clubs "absolutely" after recent reported contract rows involving high-profile players.
Denny Solomona, who scored a Super League record 40 tries in 2016 for Castleford Tigers, has "resigned" from rugby league in a bid to seal a switch of codes, according to Sale Sharks director of rugby Steve Diamond.
Solomona failed to turn up for pre-season training, but has two years left on his deal at Castleford, who say they have rejected three offers for the winger.
Meanwhile, Warrington Wolves' Chris Sandow has indicated his intention not to return, despite being under contract for another season, and James Segeyaro is reportedly unsettled at Leeds Rhinos.
Last week, Rhinos chief executive Gary Hetherington insisted Segeyaro would not be going anywhere, and on Tuesday the RFL issued a statement condemning those who appear prepared to breach the rules of their contract.
"The RFL is extremely disappointed to learn that properly contracted Super League players may not be fulfilling the terms of their employment with Super League clubs as agreed," said chief executive Nigel Wood.
"Contracts are two-way commitments mutually binding on both parties. The RFL will support its member clubs absolutely to defend their contractual positions and will work with other similarly inclined governing bodies to ensure that the unacceptable potential anarchy of lawful contracts simply being walked away from, is not tolerated."