Police discovered 450 kilograms of TNT hidden in sacks near the Egyptian border with the Gaza Strip, an Egyptian security official said on Monday.
The explosives were found in two buried deposits near Sheik Zuwayed - a village just west of the Rafah border crossing.
The official spoke on condition of anonymity because he was not authorized to speak to the media.
The find comes as Egyptian police are cracking down on tunnels used to smuggle weapons, fuel, cigarettes and foodstuff to the Palestinians in Gaza. Police have found 10 tunnels north of Rafah crossing during the past 48 hours.