L’Equipe claim the Hammers have ‘formulated an offer’ of between 15-20m euros, which works out as somewhere between £13m and £17.5m at the current exchange rate.
Toulouse have yet to respond to the offer but the Ligue 1 club must be tempted if the figures quoted by the French sports daily are correct.
Diop, a France Under-21 international, found it tough going last season as a regular in Toulouse’s line-up as Les Violets finished 18th in the table and suffered relegation from the top flight.
The report claims there is also interest from Sevilla, Everton, Fulham and RB Leipzig in the giant 21-year-old, who has two years left on his contract in France.
Cardiff City are hoping to complete a loan deal for West Ham United midfielder Robert Snodgrass, reports claim.
Manager Chris Wilder has warned it may take some time before Sheffield United bring in any new faces this summer.