RAMALLAH, WEST BANK - Palestinians marked the 60th anniversary of their uprooting with rallies, sirens and black balloons Thursday -- an annual ritual made even darker this year by crippling internal divisions and diminishing independence hopes.

The memorial provided a stark contrast to Israel's all-out birthday bash, which included a high-profile visit by President Bush for the 60th independence day celebration. Last week, Israel celebrated the Hebrew calendar anniversary of its May 14, 1948, founding with fireworks, picnics and air force flyovers.

Thursday's events commemorated the displacement of hundreds of thousands of Palestinians who either fled or were driven out of their homes during the 1948 war over Israel's creation. Palestinians call it their "nakba," Arabic for catastrophe.

The anniversary underscored the Palestinians' internal division. For almost a year now, the Islamic militant group Hamas has ruled Gaza, while the West Bank is run by moderate Palestinian President Mahmoud Abbas.

Hamas supporters stayed away from West Bank marches, while Hamas police in Gaza prevented rallies by their political rivals, including Abbas' Fatah movement.

In the West Bank city of Ramallah, thousands stood in silence in downtown Manara Square as a siren wailed, then listened to a taped Abbas speech. Some carried black flags, and at a separate event youngsters released thousands of black balloons near a West Bank crossing into Israel.

In Gaza, several thousand Hamas supporters marched toward a sealed Israeli border crossing to protest the near-complete closure of the territory since Hamas' violent takeover in June. Later, several dozen teens walked to Israeli positions on the border and threw stones. Israeli forces fired live rounds and tear gas, and Hamas police said three Palestinians were wounded.

Israel's military had sent reinforcements to the Gaza border and warned that those trying to break through the border fence were risking their lives.

In the Jebaliya refugee camp and the southern Gaza town of Rafah, Hamas police banned nakba marches by rivals, tearing down political posters, blocking streets and stopping cars. In Jebaliya, 20 Fatah supporters were detained and several others beaten by police, Fatah organizers said.

Also in Gaza, Hamas' smaller Islamist rival, Islamic Jihad, organized a march of about 500 elementary school children who marched in military-style uniforms, carrying models of rockets and fake rifles through Gaza City's main square.

This year's nakba commemorations come at a time when hopes for a peace deal with Israel are increasingly dim.

Nonetheless, Abbas pledged to push ahead with the talks. In his taped nakba speech, he warned Israel that it must not waste a peace opportunity with its continued expansion of Israeli settlements on lands the Palestinians seek for their state.

The Palestinian economy remains stagnant, despite a massive injection of foreign aid, in part because of Israel's reluctance to ease its restrictions on movement and trade.

Meanwhile, the separation of Hamas-run Gaza and the Abbas-ruled West Bank is deepening. The rivals are not on speaking terms, and the two territories that were to make up the future state are cut off from each other by Israeli travel bans.