The violence came hours after an Israeli missile strike killed a leader of Islamic Jihad and another member of the violent group in Gaza City, officials said.

Secretary of State Colin Powell said he hoped the Israeli campaign in northern Gaza - the deadliest in the strip in four years of Israeli-Palestinian fighting - would end soon.

On a visit to Brazil, Powell said the administration wants to ''see the end of these rockets coming out of Gaza and destroying the hopes of the Palestinian people and all of us for peace.''

At the United Nations, the United States late Tuesday vetoed an Arab-backed resolution that demanded an immediate end to the military operations and the withdrawal of Israeli forces.

Nearly half the 75 Palestinians killed and 60 percent of the more than 400 wounded in the campaign were civilians, Palestinian hospital officials said. Israeli troops have also demolished dozens of houses to carve out paths for tanks, mainly in Jebaliya, scene of the heaviest fighting.

In one of the latest deaths, a 15-year-old youth shot Tuesday died of his wounds, doctors said. Residents said he was standing on the balcony of his house next to the Jebaliya cap when he was shot in the head.

The father and his son died early today when an Israeli tank shell hit their house next to Jebaliya camp. Israeli military sources said soldiers returned fire at a building where militants shot an anti-tank rocket at them.

In Gaza City, an Israeli aircraft fired two missiles at a car Tuesday, killing a top official of Islamic Jihad - Bashir Aldabash, 40 - and another member of the group, Zarees Alareer. The first missile missed, but the second hit the vehicle, which burst into flames. The army said Aldabash was ''responsible for dozens of terrorist attacks.''

Later on Tuesday, an Israeli aircraft attacked a group of militants from the Al Aqsa Martyrs' Brigades in Jebaliya, according to witnesses and the militant group. The attack killed two militants and wounded two other militants and six civilians.

Israeli security officials have said targeted killings of Palestinian militants were also part of the offensive, ''Days of Penitence,'' which was launched last week, after two Israeli children, ages 2 and 4, were killed by Palestinian rocket fire on a border town.

An Israeli military official said Palestinian security officials have delivered messages through mediators, offering to try to prevent rocket fire on Israeli towns if Israel ends the operation. However, Israel appears to be in no rush to pull back.

A senior Palestinian official said he was unaware of contacts with Israel, which refuses to negotiate directly with the Palestinian Authority.

Late Tuesday, an armored Israeli bulldozer ran over a land mine, setting off a huge explosion. Then tanks fired shells, wounding three people, Palestinians said. The military had no comment.

As the resolution came to a vote in the Security Council, U.S. Ambassador John Danforth cast the U.S. veto after British and German efforts to find compromise language failed.

''It is dangerously disingenuous because of its many material omissions. Because of this lack of balance, because of these omissions, the resolution lacks credibility and deserves a 'no' vote,'' he said.

Also on Tuesday, the Israeli military said it is re-evaluating its claim that Palestinian militants used a U.N. vehicle to transport a homemade rocket.