Ayari, a Sweden international who plays in central midfield, has signed a four-and-a-half-year deal at Brighton after joining from AIK.

The 19-year-old has reportedly cost Brighton £5.2million (€6m).

"Yasin is a versatile and technical midfield player, who is good on the ball and capable of playing across the midfield," said Brighton's sporting director David Weir.

"He's had an impressive spell in Sweden with AIK, and we are delighted to have completed his transfer and to be welcoming him to the club.

"He will need time to settle here and acclimatise to the Premier League, but we are really looking forward to working with him."

While Ayari is viewed as one for the future, he may be required to step up to the first team ahead of schedule should Caicedo have his wish to leave Brighton granted in the final days of the transfer window.

Caicedo has told Brighton he wishes to leave, with league leader Arsenal having submitted a bid, reported to be £60m, last week.

The Ecuador international posted an open message to Brighton on Saturday (AEDT), saying he was "proud to be able to bring in a record transfer fee for Brighton which would allow them to reinvest it and help the club continue to be successful".

Caicedo was not involved in Brighton's 2-1 FA Cup win against Liverpool on Monday, and Arsenal is said to have lodged a new offer worth £70m.

Brighton has already sold one of its stars to the Gunners this month, with Leandro Trossard having joined Mikel Arteta's side.