Andy Carroll is on the brink of joining West Ham permanently after passing a medical with the Premier League club.
Brighton have threatened to take action against the LMA as the dispute with Gus Poyet rumbles on.
Brighton have completed the signing Latvia international Vitalijs Maksimenko from Skonto Riga.
Albion persuaded the versatile 22-year-old to move to the Amex Stadium, despite interest from a number of Premier League and Championship clubs in recent months.
Brighton manager Gus Poyet has sealed a deal for the player after he impressed during a training spell with the Seagulls late last year.
But the Albion boss has indicated Maksimenko is a long-term prospect, and unlikely to feature in the coming weeks for the club.
Poyet said: "We have been aware of him for a while. He can bring more quality to our first-team in the future.
"He has quality on the ball. He'll train with the development squad to learn the way we play. Then it's up to him."