Diop made 13 Premier League appearances last term but they came largely as a result of injuries to other players, with the 25-year-old having slipped to fourth-choice behind Kurt Zouma, Craig Dawson and Angelo Ogbonna when all are fit.
The Frenchman, who was signed from Toulouse in 2018, is entering the final year of his contract this summer, meaning this will be the Hammers’ last opportunity to command a fee unless they decide to renew his deal.
David Moyes is set to receive substantial backing in the transfer market this summer after securing a second successive season of European football, but is keen to bolster his budget by offloading the likes of Diop.
At least one new centre-back is high on Moyes’ list of priorities following the defensive injury crisis that almost derailed the Hammers’ campaign.
However, their hopes of signing Nottingham Forest captain Joe Worrall suffered a significant blow after the 25-year-old helped Steve Cooper’s side secure promotion to the Premier League with victory over Huddersfield in yesterday’s Play-Off Final at Wembley.
Worrall had been a target for several top-flight sides but seems unlikely to leave his boyhood club having ended their 23-year Premier League exile.
"It’s been a tough football club at times, and all that has been repaid today, Forest are back in the Premier League," Worrall said. "I can’t believe I’m saying those words, but we’re over the moon.
"I’m looking forward to testing myself and being on Match of the Day."