Police discovered the cache covered with bushes in northern Sinai after receiving a tip from local Bedouins, reported the official, speaking on condition of anonymity because he was not authorized to speak to the media.
Bedouins working for the authorities led them to the location of the explosives near el-Toayel village, some 25 kilometers (15 miles) west of the Rafah border crossing between Egypt and the Gaza Strip, the official said.
Smuggling across the border into Gaza or Israel has long provided a livelihood for some Bedouin. Weapons, cigarettes and foreigners seeking jobs in Israel are all taken surreptitiously across the border.
Egypt has also had problems with illicit weapons activity in the remote Sinai Peninsula. Islamic militants have carried out three major bomb attacks in Sinai since October 2004. The blasts in the resorts of Sharm el-Sheik, Taba and Dahab killed 125 people.