Hizbullah terrorists have smuggled hundreds, if not thousands, of rockets and anti-tank missiles into southern Lebanon without being detected by UN observers, senior Israeli security officials believe. Beefed-up UN forces were stationed in south Lebanon after the month-long Second Lebanon War in 2006, partially to keep the group from smuggling weapons into the area. But despite the UN presence, rockets and anti-tank missiles numbering in the high hundreds or low thousands have been smuggled into Shiite villages since the war ended, the officials said. The officials spoke on condition of anonymity because they were not authorized to discuss confidential military assessments. They offered no evidence to back up their claims, which were based on classified intelligence reports. In Beirut on Sunday, a Hizbullah spokesman said, "We don't comment on security and military affairs." Yasmina Bouziane, spokeswoman for the 13,000-strong UNIFIL peacekeeping force would not comment on the report Sunday. The UN troops patrol a buffer zone near the border with Israel with the help of 15,000 Lebanese soldiers. The force was deployed after the war to help the Lebanese extend their authority into the south for the first time in decades and create a buffer zone free of Hizbollah fighters. Hizbullah has maintained a low profile in south Lebanon since the conflict, but Israel believes the quiet has masked a concerted rearmament effort. Israel claims Hizbullah has smuggled arms in shipments marked as civilian, with most thought to have arrived from Iran through Syria. Some of the group's new missiles are capable of striking south of Tel Aviv, security officials have said. Syria and Iran have denied moving weapons into Lebanon. But last year, the UN Security Council expressed "grave concern" about the reports of arms smuggling to Hizbullah. Security officials estimate that more than 20,000 rockets are deployed in Lebanon, including north of the Litani River - outside the jurisdiction of the UN forces. Before the war, Hizbullah had 13,000 rockets deployed, Israel estimates.