The latest sweep for militants in the West Bank town of Qalqilya came amid rising tensions over Israeli Prime Minister Ariel Sharon's plan to uproot Gaza settlements while tightening Israel's grip on much of the West Bank -- a tradeoff Palestinians have rejected.

A new Israeli newspaper poll reinforced signs of eroding support for Sharon's plan within his right-wing Likud party, which will hold a May 2 referendum on the issue. The survey showed 49 percent in favor of the proposal and 39.5 against it.

Mindful of opposition within the Likud's pro-settler ranks, Sharon signaled on Thursday that he would likely press ahead with his proposal even if his own party rejected it.

The latest series of army raids and sweeps could help shore up support for Sharon, who has tried to calm Israeli fears that a Gaza withdrawal might encourage stepped-up attacks by militants claiming it as a victory.

Witnesses said Israeli commandos in an unmarked car opened fire on four men in Qalqilya killing three and wounding the fourth, identified as the local leader of al-Aqsa Martyrs Brigades.

The army said soldiers fired after the men ignored orders to halt and tried to flee, but witnesses described it as an ambush.

A senior official of al-Aqsa, a militant faction of the Palestinian president's Fatah movement, said one of the dead belonged to the armed group but the other two were political activists.

An Israeli army spokesman said the men were all militants on Israel's wanted list.