JERUSALEM—A top Israeli defense official says Gaza is being flooded with sophisticated weapons from Libya and that the anti-aircraft missile fired last week at an Israeli helicopter likely originated there.

Yossi Kuperwasser, who directs the Ministry of Strategic Affairs, says "significant" numbers of weapons have been smuggled into the territory from Libya since the fall last year of dictator Moammar Gadhafi. The country is awash in weapons after the eight-month civil war and has weak central authority.

Palestinian militants in Gaza launched a shoulder-fired Strela missile at an Israeli helicopter last week, but missed. It was the first such launch from Gaza.

Kuperwasser said Wednesday that Israel has long assumed that Gaza militants have kept such weapons, but probably only fired them after they amassed a large enough stockpile.