Arsenal have reached an agreement with Brighton to sign Belgium forward Leandro Trossard, the PA news agency understands.

The Gunners have been in the market to bolster their attacking options in the January transfer window and have now agreed a fee for the 28-year-old.

The PA news agency understands a deal has been struck worth £21million plus add-ons.

Leandro Trossard in action for Belgium
Belgium international Leandro Trossard is set for a switch to the Emirates Stadium (Nick Potts/PA)

Arsenal are keen to add strength in depth to their attacking options ahead of the Premier League title run-in, with summer signing Gabriel Jesus still some time off returning from a knee injury suffered at the World Cup.

They were close to agreeing a move for Mykhailo Mudryk, only to be gazumped by Chelsea after a delegation from the Blues travelled to Turkey to strike a deal with Shakhtar Donetsk which instead took the winger to Stamford Bridge.

While Chelsea paid a reported up-front fee in excess of £60million for Mudryk, Trossard is likely to cost much less than that.

Trossard, who featured in all three Belgium fixtures in the World Cup in Qatar, was not part of the Brighton squad that beat Liverpool 3-0 on Saturday.

Seagulls boss Roberto De Zerbi openly questioned the forward’s attitude as links to Tottenham began to emerge.

League leaders Arsenal, though, were quickest to move and have managed to strike a deal with Brighton, who have a recent history in earning a premium for their key stars.

On Thursday afternoon, the Football Association announced Arsenal had been fined £40,000 after their players surrounded the referee during the FA Cup third-round tie at Oxford as they appealed for a penalty.

Arsenal denied the allegation of failing to ensure players conducted themselves in an orderly fashion and also requested a hearing, but the charge has been upheld.

A statement from the FA read: “An independent regulatory commission subsequently upheld the allegation and imposed the club’s fine. Its written reasons for these decisions will be published in due course.”