The former Metz striker bagged twelve goals across all competitions during his debut campaign in East London, including ten strikes in the Premier League.
But the Senegal international has seen his game-time reduced since Slaven Bilic replaced Sam Allardyce as Hammers gaffer last summer, issued just 18 starts in the Premier League last season.
The Irons have made no secret of their ambitions to sign a top-class striker this summer, with bids for the likes of Bournemouth’s Callum Wilson and Lyon’s Alexandre Lacazette, which will likely see Sakho plummet further down the pecking order next season.
Accordingly, the 26-year-old has handed in a formal transfer request at the Olympic Stadium.
That follows an £11million bid from Allardyce’s Sunderland last month. The Hammers rejected the offer, but the Stadium of Light outfit are expected to revive their interest upon news of Sakho’s availability.