Israel fears that Hamas is working to build unprecedentedly large tunnels along the Philadelphi Corridor that will be used to smuggle long-range rockets into the Gaza Strip in one piece, senior defense officials have told The Jerusalem Post. Before Operation Cast Lead was launched in late December, Hamas was believed to be operating several hundred smuggling tunnels along the 14-kilometer strip of land separating the Gaza Strip and the Sinai Peninsula. "Hamas is working on obtaining new advanced weaponry and extending the range of its rockets," a senior defense official told the Post. "In order to get this weaponry into Gaza, it will need larger tunnels than it currently has." Digging a smuggling tunnel is considered a complicated and sometimes dangerous operation that can take several months, depending on the tunnel's length and size. The tunnels along the corridor vary in size, but some are believed to be large enough for a person to stand inside. According to Military Intelligence, the long-range Katyusha rockets Hamas fired into Ashdod and Beersheba during the recent operation were smuggled into Gaza in several pieces. These rockets are manufactured in Iran in a number of pieces, enabling their fairly easy transfer to Gaza. Other rockets that Hamas would like to get its hands on include the long-range Iranian-made Fajr, which has a range of 70 km. and could reach as far as the outskirts of Tel Aviv. Unlike the Grad-model Katyusha, which is 2 meters long, the Fajr is close to 10 m. and is not easy to assemble if smuggled into Gaza in components. Some of the reports on the alleged Israeli air strike against a weapons convoy in Sudan and bound for Gaza have claimed that the trucks were carrying Fajr missiles, a weapon that could alter the strategic balance of power between Israel and Hamas. Last week, Shin Bet (Israel Security Agency) chief Yuval Diskin told the cabinet that since the three-week military operation ended on January 18, Hamas had smuggled 22 tons of explosives, 45 tons of raw materials for producing bombs, dozens of rockets, hundreds of mortar shells and dozens of anti-tank and anti-aircraft missiles into Gaza. Defense officials called on Egypt to increase its efforts to stop the smuggling along the Philadelphi Corridor. "It really all depends on the Egyptians in the end, since they are deployed along the border and, if they want, can stop the smuggling," one official said.