The NFL sent a letter to all 32 teams reminding them about the rules before free agency begins Tuesday and stating the league’s displeasure with the release of early contract terms.

“The memo makes clear that we will look into any potential violations of the rules,” NFL spokesman Greg Aiello said Monday.

The NFL sent the memo after news leaked of agreements between high-profile free agents and teams.

NFL free agents are permitted to officially sign with other teams on Tuesday at 4 p.m. ET, but a three-day negotiating period began Saturday during which teams can meet with representatives of free agents. Teams also are not permitted to agree to contracts with players on other teams during the negotiating period.

“You are reminded that the purpose of the three-day negotiating period is to create a level playing field in the competition for Unrestricted Free Agents, by permitting clubs to express interest in a prospective UFA and to exchange information with certified agents regarding the level of compensation envisioned by the club and the agent,” the NFL wrote in the memo. “Any attempt to undermine the purpose of this negotiating period may be considered conduct detrimental to the League.

“At this time, the League office is beginning investigations into a number of reported agreements with clubs. Violations will be dealt with accordingly.”