West Ham are reluctant to sell and will refuse to listen to offers of less than £60m for the defender, according to Sky Sports.
Diop made 38 appearances for the Hammers last season, completing 90 minutes in every outing and scoring twice.
Other targets Manchester United are rumoured to be considering are Napoli centre-back Kalidou Koulibaly, who would cost around £100m and Harry Maguire, who Leicester City value at £80m.
Solskjaer is also looking to raid another London club for a defender, with talks apparently ongoing for Crystal Palace full-back Aaron Wan-Bissaka.
NOW THIS
5 big Premier League games to watch out for in 2019/20
‘Sir Gary Lineker? I don’t know how you comment on that – I’ve never even considered it. I just try to stand up for the things I believe in’ England legend tells FFT why he won’t stop raising humanitarian issues, even if it affects potential honours
'I fell on the floor and shouted for a penalty. Someone pulled me up and said, "Don’t cheat to win penalties". It was Steve McManaman. I never did it again!' Ex-Liverpool forward reveals harsh lesson he learnt from his team-mate on Reds debut
