BETHLEHEM, West Bank?Israeli tanks and bulldozers rumbled into more Palestinian towns and massed on the edge of Bethlehem in an expansion of their West Bank offensive Monday, as Palestinian militants killed 10 suspected collaborators ahead of the advancing Israeli troops.

The Israeli advances came after Prime Minister Ariel Sharon said in a televised address Sunday night that Israel was “at war” and branded Palestinian leader Yasser Arafat “an enemy of Israel,” blaming him for a bloody series of suicide bombings against Israelis. Sharon vowed to uproot a “terrorist infrastructure” he said Arafat has built up.

Arafat has been trapped in his offices in Ramallah, surrounded by Israeli soldiers, since the first day of the offensive on Friday, and his aides say he has no way to call a cease-fire while confined. At least 22 Palestinians and two Israelis have been killed in Ramallah fighting since Friday.