Brentford have signed West Ham defender El Hadji Malick Diouf in a deal worth up to £40m.

The 21-year-old Senegal left-back has joined on a five-year contract, with the club having an option to extend it by a further year.

The move sees Brentford paying an initial £35m for the player, with a further £5m in add-ons.

Diouf played in West Ham’s Championship opener against Burnley, but was excluded from the matchday squads of the Hammers’ following two games as a deal was worked on.

He was the Bees’ priority defensive target in this transfer window, but discussions had stalled this summer before being reopened earlier this week.

Diouf is returning to the Premier League after suffering relegation with the Hammers last season.

And his sale represents a big profit for West Ham on a player they paid Slavia Prague £19m for a year ago.

Diouf played 34 times for West Ham last season, providing five assists.

“He’s a player that fits our ideal age profile, with lots of room to still develop,” Brentford head coach Keith Andrews said.

Diouf said Andrews had convinced him he could continue to improve at the club.

And when asked about his ambition upon joining his new club said: “Why not win the league?”

He is Brentford‘s fifth summer signing of the summer after the arrivals of striker Callum Wilson, midfielder Mamadou Sangare, centre-back Jannik Schuster and winger Jaidon Anthony.

After breaking into the Senegal side last year, Diouf played four times at the World Cup this summer.

While West Ham were relegated after finishing 18th last season, Brentford enjoyed an excellent campaign under Andrews, finishing ninth and just missing out on European football on goal difference.

Brentford began their season on Saturday with a 3-0 win over Tottenham Hotspur and play Leeds on Sunday in their next league game.