West Ham are willing to offer €18 million for Basel defender Manuel Akanji.
Swiss journalist Andreas Boeni says the player is also wanted by Borussia Dortmund.
Liverpool, Tottenham Hotspur and Southampton have also been linked with Akanji, who is valued at around €20 million by the Swiss clubb.
The 22-year-old is due to feature in the Champions League last 16 for Basel next month when they face Premier League leaders Manchester City.
He impressed in the group stages against Manchester United, sparking talk of a move during the January transfer window.