West Ham announced Thursday that Swiss midfielder Edimilson Fernandes had joined the Premier League club from FC Sion for an undisclosed fee.

The 20-year-old was introduced on the pitch of the Hammers' London Stadium ground before kick-off in Thursday's Europa League qualifier against Romanian side Astra Giurgiu.

Fernandes, the cousin of former Manchester City and Leicester midfielder Gelson Fernandes, has signed a four-year contract.

He is the ninth signing completed by Hammers manager Slaven Bilic during the current transfer window.