Bunley’s Dwight McNeil is also on the Hammers’ radar as the club looks to improve on its 7th place finish in the Premier League last season.
The Scot’s preference is to make a move for the Rovers forward, who is coming off the back of an impressive campaign at Ewood Park.
The Chile international scored 22 goals in the Championship as Tony Mowbray’s side finished 8th in the table.
Brereton Diaz also only has one year remaining on his contract with the club, so a sale may be agreed to in order to cash-in on a valuable asset.
Otherwise, Rovers risk losing the striker for nothing in a year’s time.
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Blackburn may yet face competition to sign the 23-year old, with Leeds United also interested in making a move for the player.
The Stoke-on-Trent born player had a breakout campaign last year as he asserted himself as one of the most important members of Blackburn’s squad.
Jon Dahl Tomasson has taken charge of the team this summer, with preparations now well underway with the new campaign a little over a week away.
There has been mounting speculation that Premier League interest will arrive for Ben Brereton Diaz.
Blackburn could command quite a high fee for the forward, even with only a year left on his contract, which would significantly soften the blow of his absence.
A deal should be sought after quickly if Blackburn are going to commit to selling so that there is ample time in the window remaining to reinvest the money earned.
Reinforcements will be needed regardless given the loss of Joe Rothwell, Darragh Lenihan and Ryan Nyambe from last season’s squad.