Well, Najim, I dont have any official or proper link to prove that it has reached as high as 60C in the desert. But yes it has been observed by many people working here in the desert.
Also many monitoring stations at SAUDI ARAMCO wells and refineries deep inside the desert have recorded as high as 60C. But these figures are never made public due to some strange policies here in the Kingdom.
Btw, check this article as well.. KSA temp to reach 80 C