A Hamas leader affirmed the group's hard-line principles in a speech to thousands of Muslim worshippers Sunday, as they commemorated the uprooting of Palestinians during the 1948 war over Israel's creation.

Palestinians mark the occasion this year "with great hope of bringing to an end the Zionist project in Palestine," Ismail Haniya, the prime minister of the Hamas government in Gaza, told about 10,000 people at a Gaza City mosque.

Haniya's apparent reference to Israel's destruction could prove embarrassing for Western-backed Palestinian President Mahmoud Abbas. He recently reconciled with Hamas after a four-year split and is trying to market the Islamic militants to the international community as an acceptable political partner.

Marches commemorating the 1948 events, known in Arabic as "nakba," or the "catastrophe," were also planned in the Abbas-ruled West Bank and in Arab towns in Israel.

Hundreds of thousands of Palestinians fled or were driven out during the fighting more than six decades ago. The dispute over the fate of the refugees and their descendants, now several million people, remains at the core of the Mideast conflict.

Israeli security forces were on high alert Sunday, and the Israeli military sealed the West Bank for a day, barring Palestinians from entering Israel.

Haniya launched the nakba commemorations with a dawn sermon at Gaza City's al-Omari Mosque.

He said Palestinians have the right to resist Israeli occupation and will one day return to property they lost in 1948. "To achieve our goals in the liberation of our occupied land, we should have one leadership," Haniya said, praising the recent unity deal.

As part of the that agreement, Hamas and Abbas' Fatah movement are to share power in a transitional government until elections are held next year. The U.S. and Europe consider Hamas a terrorist group and have said they will only deal with it if it renounces violence, recognizes Israel and honors previous peace commitments made by the Palestinians.

Haniyah reiterated Sunday that his movement would not recognize Israel at the outset.

However, Hamas leaders are often vague or issue contradictory statements about the group's political aims.

In recent weeks, some in the group have spoken of reconciliation with the West and a halt to armed hostilities with Israel, and even hinted at some sort of political accommodation with the Jewish state.

While Israel is not convinced, there are hopes in some Palestinian circles that the Iran-backed group could become a more accepted part of the Mideast diplomatic equation.