OCCUPIED JERUSALEM, 23 September — Thousands of Palestinians yesterday broke a punishing curfew in the West Bank and Gaza Strip to protest the siege of their leader, Yasser Arafat. Israeli troops shot dead five of them.

The mass protests were the first sign of popular support for the Palestinian president since Israeli tanks and bulldozers assaulted his West Bank headquarters on Thursday and prompted aides to suggest the army’s blockade could backfire.

Tightening a siege, the army cut telephone lines and power to Arafat’s shattered compound in the city of Ramallah as heavy machinery worked to demolish the buildings around him.

But buoyed by support from protesters, Arafat vowed never to surrender to Israeli Prime Minister Ariel Sharon and refused to hand over 50 men who Israel says are holed up with him in his devastated presidential headquarters.

“We will hoist the flag of Palestine above the walls, churches and minarets of Jerusalem...May God make me a martyr,” Arafat said defiantly in excerpts of a telephone conversation with an Israeli Arab lawmaker broadcast on Israel television.

Hatem Abdel Khader, a Palestinian aide who spoke to Arafat by telephone, said: “He reiterated he will not kneel before Sharon and has issued an order to his men that no one may surrender from the building.”

Prince Abdullah, the regent, and US Vice President Dick Cheney discussed the siege in a telephone conversation. The two men discussed “developments in the region, particularly on the Palestinian scene, the dangerous (Israeli) escalation and aggression against the Palestinian people and its leadership,” the Saudi Press Agency said.

The United States repeated its misgivings over Israel’s actions in Ramallah, calling them “not helpful” to peacemaking efforts. Britain said it was lodging a formal protest with Israel, in the latest European censure of the Israeli siege.

Israel had said earlier about 20 suspects were hiding with Arafat. The number was raised to 50 after people leaving the headquarters area were questioned by Israeli security services.

Marching under pictures of the Palestinian leader and chanting “We will give our soul and blood for Arafat”, protesters poured onto streets after midnight.

Palestinian hospital officials said two protesters were shot dead overnight in Ramallah and two others were killed in the early hours of the morning in the northern West Bank. Palestinian hospital sources said a soldier killed a teenager who defied curfew in the West Bank city of Nablus.

The bloodshed prompted new rallies in Gaza City and in Hebron, Tubas, Salfit and Bethlehem in the West Bank. Calling Arafat a “symbol of peace and freedom”, hundreds of people demonstrated in Bethlehem under posters of their leader. “We are all under siege,” they shouted.

In Tubas, thousands hailed Arafat by his nom de guerre, chanting: “Go, go, Abu Ammar. We’re behind you until liberation.”

The siege raised fears of a new surge of bloodshed that could complicate Washington’s plans for possible war on Iraq.

Suggesting the siege could backfire by rallying support for Arafat among his disgruntled population, Palestinian Labor Minister Ghassan Al-Khatib said: “It is strengthening Arafat. It is giving (him) public sympathy and public credibility.”

Almost all the buildings in Arafat’s presidential compound have now been demolished by armored bulldozers and he is at the mercy of the troops surrounding him.

“Israeli actions in and around the Muqaata (headquarters) are not helpful in reducing terrorist violence or promoting Palestinian reforms,” a White House spokeswoman said.

British Foreign Secretary Jack Straw said he had instructed his ambassador to Israel to raise the country’s “concerns” with the Sharon government over the handling of the siege. “This blockage and damage to President Arafat’s compound is not justified. I urge an early end to this action,” Straw said. But Palestinian negotiator Saeb Erekat expressed regret at the lack of international concern. “All our contacts with the Israelis, Europeans and Americans have failed to produce any tangible results,” he said.

The demolitions stopped in the afternoon, and soldiers strung barbed wire around the compound. Photos released by the Palestinian Authority showed a grim-looking Arafat perusing documents, with bottles of mineral water on his desk and his holstered gun placed behind him.