Alex Baptiste is hoping there will be a permanent deal to be done with Blackburn at the end of his season-long loan.
Sky Sports sources understand that Leicester have agreed a fee with Wigan for James McArthur.
The 34-year-old has agreed terms with Blues and passed a medical but the club are waiting on a visa application before a one-month deal is completed.
Former Senegal international Diop, who helped West Ham to promotion to the Barclays Premier League last season, has impressed on trial at St Andrew's.
He has also played in England for Fulham and Portsmouth, with whom he won the FA Cup in 2008.