The defensive midfielder is expected to link up with his international team-mates on January 5 and could be out until mid-February should the Eagles reach the final.
Diakite's absence will be a big blow to QPR, who are eight points adrift of safety at the bottom of the Barclays Premier League.
Meanwhile, QPR will be able to call upon DJ Campbell again from Thursday onwards.
The 31-year-old has impressed during a loan spell at Ipswich, netting 10 goals in 16 appearances.
Campbell's earlier-than-scheduled return will boost the Hoops, who could include the striker in their FA Cup clash with West Brom on January 5.