Sky sources report that West Ham have made a £4million bid for Boca Juniors defender Emanuel Insua.
The 23-year-old left-back is the younger brother of former Liverpool defender Emiliano Insua and Boca are reportedly open to offers for his services.
West Ham have made a number of moves in the transfer market this summer and Insua would be their sixth new arrival if a deal can be agreed.
The Hammers have already landed one Argentinian, having signed Velez Sarsfield forward Mauro Zarate in May.
And they have just completed a deal for Enner Valencia, the Ecuador forward who made a big impact at the World Cup in Brazil.