In addition, Israeli officials say Hamas has recruited 10,000 fighters in Gaza for its so-called Executive Force, a unit that receives military training and shares headquarters with the Qassam brigades, Hamas' military wing, The New York Times reported.
Despite reports of Hamas' improved rocket range that would allow a rocket to hit the Israeli town of Ashkelon, "we are not going to start a big operation in Gaza," an Israeli military commander told the Times in an exclusive interview published on the condition of anonymity.
But Israeli Prime Minister Ehud Olmert is under pressure from the political right and others to deal with the Hamas buildup, the official said.
Yuval Diskin, director of the Shin Bet internal security service, told journalists recently if the buildup continues, "at the end of the day we will have to do something about it." Among other things, Diskin said Egypt must do more to stop the smuggling of weaponry and explosives into Gaza.
Hamas denies sending men to Iran for training, dismissing Israel's assertions as propaganda designed to hurt the Palestinian government.