Jerusalem ? The leaders of violent Islamic groups are targets for assassination, Israel’s defense minister said Sunday, raising the possibility of a further escalation in the three years of Israeli-Palestinian bloodshed.

Shaul Mofaz issued the threat in response to a declaration by the spiritual leader of Hamas, Sheik Ahmed Yassin, that the group plans an all-out effort to kidnap Israeli soldiers.

“The statements of Yassin just emphasize the need to strike the heads of Hamas and the Islamic Jihad,” Mofaz told the weekly meeting of the Israeli Cabinet, according to an Israeli official who attended the meeting.

The statements by Mofaz and Yassin threaten to inflame an already violent confrontation that has led to the deaths of more than 3,500 people on both sides during three years of fighting.

Last week, Israel killed eight Palestinians in a shootout in Gaza City, while a Palestinian suicide bomber killed 11 people in Jerusalem. Hamas took responsibility for the bombing, a day after a claim from the Al Aqsa Martyrs’ Brigades, loosely linked to Palestinian leader Yasser Arafat’s Fatah movement.

Sunday was a Muslim holiday, and Hamas officials were not available to react to Mofaz’s comments.

During more than three years of violence, Israel has carried out many pinpoint attacks aimed at leaders of Hamas and Islamic Jihad — often prompting a violent response.

But Israel has greatly reduced the number of targeted killings in recent months. Last month, Mofaz’s deputy, Zeev Boim, retracted comments calling for Yassin’s assassination, saying later that no decision had been made.

Hamas, responsible for dozens of suicide bombings during the past three years, also appeared to have scaled back its activities until a Hamas female suicide bomber killed four Israelis at a Gaza-Israel checkpoint Jan. 14.

Yassin encouraged kidnapping Israeli soldiers a day after Israel released 400 Palestinian prisoners as part of an exchange with the Lebanese militant group Hezbollah for a businessman and the bodies of three soldiers.