Egyptian security forces have uncovered 13 tunnels used by smugglers to slip contraband into the Gaza Strip, a security official said on Monday.

Three of the tunnels collapsed after heavy rain along Egypt's border with the Palestinian territory, the official said, adding that the remaining tunnels would also be destroyed.

There were no reports of casualties after the tunnels collapsed. At least 40 Egyptian and Palestinian smugglers have died in tunnel accidents and demolitions by Egyptian security forces this year.

The Rafah border post with Egypt is the only crossing into Gaza not controlled by Israel, which has enforced a blockade on the territory since Hamas, which Israel regards as a terrorist group, seized power there in 2007.

Israel says Palestinians use the tunnels to smuggle weapons into Gaza and has asked Egypt to do more to close them.

Palestinians say the tunnels are a lifeline for the territory, where the United Nations says more than half of residents live below the poverty line.

Egypt occasionally allows Palestinians to enter and leave Gaza through the Rafah crossing, but has refused to open it permanently.

The security official said that Egypt would open Rafah for three days from Tuesday, to allow Palestinians stranded on the Egyptian side to enter Gaza and some sick Gazans, and holders of foreign passports, to leave.