Israeli helicopters blasted a Gaza City building with missiles on Wednesday, killing a suspected militant, one of several violent incidents on a day also marked by Israeli statements about Palestinian statehood.

Prime Minister Ariel Sharon said that as part of the U.S.-sponsored "road map" for Mideast peace, Palestinians could set up a temporary state in part of the West Bank and much of Gaza. But Foreign Minister Benjamin Netanyahu said that even before peace talks, Palestinians would have to give up their demand to relocate millions of refugees in Israel.

In Gaza City, the pair of Israeli helicopters fired several missiles at a cinderblock hut used by security guards at a Palestinian government complex, killing the uniformed guard, Mustafa Sabah, 35, Palestinians said.

According to the Israeli army, Sabah was involved in three powerful roadside bomb attacks against Israeli tanks in Gaza that killed seven soldiers from February to September of this year.

Hours later, about 10 Israeli tanks backed by helicopters moved into Gaza City early Thursday and raided a house, witnesses said. There were no immediate reports of casualties and the Israeli military had no comment. The incursion was in the Sheikh Ajlin neighborhood in the southern part of the city, the witnesses said.

Israel has carried out dozens of targeted killings against suspected Palestinian militants during the past two years of Mideast fighting.

The Israelis say the operations are self-defense, but Palestinians and human rights groups object to the practice. Palestinians charge the Israelis are killing their leaders, and human rights groups complain the operations are summary executions without judicial process.

In the West Bank village of Tufah, Israeli troops searching caves for members of the militant Islamic Jihad group came under fire, the army said, and soldiers shot back, killing two men.

Also, Israel said it detained an American doctor for two weeks on suspicion he was linked to Al Qaeda, before releasing him without charge. The U.S. Embassy said there was no evidence linking him to any terror group.

Dr. Khaled Nazem Diab, 34, arrived in Israel on Nov. 14 on a mission for the Qatari Red Crescent to train Palestinian social workers, said Farek Hussein, director for the Palestinian Red Crescent.

Diab was detained at the airport and held until his release last week, then deported to Jordan, Hussein said.

"We have no evidence that he was involved in terrorist activity," said U.S. Embassy spokesman Paul Patin. "He's a qualified doctor. He's been in and out of the [Palestinian] territories doing humanitarian work with children."

A week after his deportation, Israel's government press office released a statement Wednesday saying Diab was suspected of funneling money to Al Qaeda and other unidentified terror groups.

Diab worked with an Islamic charity group, al-Najda, which has been investigated and shut down in the United States, the statement said. Israel claimed Diab lived in Afghanistan and was in close contact with groups that identify with the Taliban. The statement also said Diab had contacts with activists connected to the militant Hamas.

Israel did not provide evidence to support the claims.

In the West Bank city of Nablus, Israeli troops shot and critically a 15-year-old Palestinian youth after he pointed a toy gun, Palestinians said. The Israeli military said soldiers fired at armed Palestinians.

In Gaza, a 12-year-old boy and his father were killed in a clash between rival Palestinian groups arguing over who would write graffiti on a wall, witnesses and doctors said.

Addressing a security conference north of Tel Aviv, Sharon and Netanyahu said the Palestinian leadership must be replaced.

Sharon said a three-phase peace plan presented by President Bush, with the backing of the European Union, Russia and the United Nations, "can be implemented."

The plan calls for a provisional Palestinian state before agreement on main issues like Jerusalem, refugees and borders are settled. Netanyahu said the Palestinians must drop their demand to give millions of refugees from the 1948-49 war that followed Israeli creation and their descendants the right to return.

Sharon said, "Israel will not return to rule territories from which we withdrew under political agreements." Israel turned control of most populated Palestinian areas under the accords, but in recent months Israeli troops have reoccupied many of them in response to homicide bomb attacks in Israel. In his address, however, he said the areas would make up a Palestinian state in the second phase of the Bush plan.

However, he said that the first steps must be an end to Palestinian violence and a change in the leadership.

A Palestinian leader jailed in Israel has been sent to solitary confinement for five days because he gave an interview to The Associated Press, his lawyer and a prison services official said Wednesday.

Marwan Barghouti answered questions through his lawyer, Khader Shkirat. In the interview, published Tuesday, Barghouti called for replacing the Palestinian leadership and expressed support for violent resistance against Israeli occupation of Palestinian areas.

Prison Services spokeswoman Orit Messer-Harel said Barghouti was punished for violating a ban against giving interviews without permission. Barghouti is on trial for his alleged role in attacks that killed 26 people.