At least two soldiers were killed Saturday when a smuggling tunnel connecting Egypt's restive Sinai Peninsula and the Gaza Strip collapsed, a security source said.The tunnel, close to the Rafah border crossing, crumbled after the troops got in to destroy it, Xinhua quoted the source as saying, adding that two other conscripts were still missing and another two injured.The tunnels were used to transport foods and commodities to the Gaza Strip, which has been under Israeli blockade since 2007, but the authorities believed they were also used to smuggle weapons and militants into Egypt.Egyptian military have destroyed more than a thousand of tunnels in the border areas since 2011, especially after the start of an operation last July against Islamist militants in Sinai.