The 22-year-old is currently owned by Deportivo Maldonado but made his name with Boca Juniors and is currently on loan at Sao Paolo.
Indeed, Calleri bagged 23 goals in 59 appearances for Boca, helping them lift the Primera Division title and Copa Argentina in 2015, and has netted 16 times since signing for Sao Paolo in January.
The 5 foot 10 forward has been linked with West Ham for much of the summer transfer window and Jack Sullivan, son of Hammers co-chairman David, announced he’d be signing for the East London club last week.
According to London Evening Standard, the Hammers are now on the verge of announcing a loan deal for Calleri.
He’s set to become the Irons’ eighth signing of the summer, following deals for Sofiane Feghouli, Havard Nordtveit, Domingos Quina, Toni Martinez, Ashley Fletcher, Gokhan Tore and Manuel Lanzini