The French club indicated on Sunday that the 23-year-old, who is part of Mali's African Nations Cup squad, is on his way to Rangers, though a spokesman for the Premier League club confirmed to Press Association Sport that the deal has yet to be finalised.
Diakite would become manager Mark Hughes' third signing since taking over from Neil Warnock at Loftus Road, following the arrival of defenders Taye Taiwo and Nedum Onuoha.
A statement on the Nancy website suggested terms had already been agreed but also that no contract had yet been signed by the player.
It read: "Samba Diakite is officially on loan to English club Queens Park Rangers until the end of the season. This loan will change automatically to a permanent transfer if the London club, currently 16th, stay clear of the relegation zone.
"Currently in Gabon with the Mali squad competing in the African Nations Cup, the player has received permission from coach Alain Giresse to make the round trip to London to undergo a medical and to sign his contract."