About 477 Palestinians were released from prison last October in a deal that freed kidnapped Israeli soldier Gilad Shalit.
Prior to the deal, some officials worried the sudden influx of prisoners into the Gaza Strip would cause an increase in major terror attacks, Ynetnews.com reported Wednesday.
Data released by the Israeli daily newspaper Yedioth Ahronoth indicated many of the prisoners have joined the leadership of Hamas and others are developing weapons and firing on Israel.
A senior Israeli defense official said an increase in major attacks so far has not materialized despite an increase in terrorist activity.
"Their will to execute acts of terror is getting stronger, but the coordination with the Palestinian authorities is effective and Israel knows how to sophisticatedly track the released terrorists," the official said.
"Several terror attacks have been successfully prevented thanks to the hard fieldwork," he added.
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