Jerusalem  - US President George W Bush opened a 48-hour visit to Israel Wednesday by reaffirming Washington's "enduring alliance" with the state.

Calling Israel a "true democracy," Bush told Israeli President Shimon Peres in Jerusalem that "I suspect that if you look back 60 years ago ... I doubt people would have been able to foresee the modern Israel."

"What happened here, could happen everywhere."

Bush is visiting Israel as it is celebrating 60 years since it declared statehood on May 14, 1948. He is to address an international conference marking the state's 60th anniversary, attended by key world leaders and hosted by Peres, late Wednesday, as well as Israel's Knesset (parliament) Thursday afternoon.

In a series of meetings with Israeli leaders before his departure Friday, he will also be briefed on the difficult Israeli-Palestinian peace negotiations, which - under his auspices - were revived late last year for the first time in seven years.

Unlike during his first visit in January, Bush will not travel to Ramallah. But he will be briefed on the talks by the Palestinian side in meetings with President Mahmoud Abbas and Acting Prime Minister Salam Fayyad in Sharm el-Sheikh, Egypt on Saturday and Sunday.

"It's good to be back again," Bush said at a festive welcoming ceremony at Israel's Ben-Gurion International Airport earlier Wednesday.

"We our proud to reaffirm the friendship of our peoples," he said. Israel and the US were founded on the same democratic principles, faced similar challenges and over the years built an "enduring alliance to confront terrorists and tyrants."

Olmert called Israel's alliance with the US "one of the fundamental pillars of our national security."

"Since assuming office almost eight years ago, President George W Bush has been our closest ally and partner," he said, calling Bush's decision to attend Israel's 60th anniversary celebrations "an extraordinary gesture of friendship."

As many as 14,000 police were deployed to secure the Bush visit, codenamed "Operation Clear Skies 2," a number higher even than the 10,000 which safeguarded Bush's first visit in January.

As Israel continued its celebrations - begun already last week according to the Jewish calendar - Palestinians throughout the West Bank and Gaza began marking the 60th anniversary of the 1948-1949 Arab-Israeli war that erupted following Israel's creation.

The war, during which hundreds of thousands of Palestinian refugees fled their homes in what is now Israel, is known to them as the Nakba - catastrophe in Arabic.

Hundreds of Palestinians clashed with Israeli troops at a number of military checkpoints in the West Bank. Some six people were reported injured at the Qalandia checkpoint, north of Jerusalem, when the troops responded to stone-throwing with rubber bullets and teargas.

In Gaza, senior Hamas official Mahmoud al-Zahar told a conference commemorating the Nakba his movement would "never" recognize Israel.

"Israel is going to disappear one day and the Palestinian people will remain to fully liberate all their occupied land," he told a cheering audience, referring to all of historic Palestine.

Palestinians' "right of resistance," including rocket attacks from Gaza, "is holy."

The rocket attacks, and Israel's retaliatory airstrikes, ground raids and paralyzing economic blockade of the Hamas-ruled Strip, have cast a dark shadow over the revived peace talks.

Palestinians are also angered with Israel's declarations that it will not stop building in a number of a key West Bank settlement blocks, which it has vowed to keep under any final peace deal.

But despite the Gaza violence and bitter argument over settlement construction, Bush said prior to his departure that he believed a peace deal before he leaves office in January 2009 is still possible.

Israeli Prime Minister Ehud Olmert said on the eve of the Bush visit that his and Abbas' negotiating teams have in their past five months of talks made "significant progress."

"Points of agreement have been reached in important matters, but not on all of the issues," he said in his address late Tuesday to the three-day Jerusalem conference hosted by Peres.

Palestinian officials, however, have downplayed the Israeli statements of progress.

"There is still a big gap between us and them regarding all final final status issues. We hope to bridge this gap," senior Palestinian negotiator Saeb Erekat told Voice of Palestine Radio Wednesday.

He nevertheless called the negotiations "serious and in-depth" and said they dealt with all the core issues of the Israeli-Palestinian conflict "without any exception." (dpa)