Tens of thousands of Palestinians packed a memorial service for the late Yasser Arafat on Sunday, providing a massive show of support for his successor, President Mahmoud Abbas, as he prepares for peace talks with Israel.

Speaking under a giant mural of a smiling Arafat at the burial site of the longtime Palestinian leader, Abbas repeatedly invoked Arafat's memory to bolster his own leadership. He pledged to lead the Palestinians to independence and took aim at his rivals, the violent Islamic Hamas.

"Our strategic decision is peace," said Abbas, echoing one of Arafat's favorite slogans.

Abbas has been meeting regularly with Israeli Prime Minister Ehud Olmert ahead of a peace conference in Annapolis, Maryland, later this month. The conference is expected to kick off Israeli-Palestinian peace negotiations, which broke down in violence seven years ago.

The upcoming conference, Abbas said, is "a historic opportunity to make a new page in the history of the Middle East."

A new hitch developed Sunday when chief Palestinian negotiator Ahmed Qureia said his delegation, on its way to meet Israel's foreign minister about a pre-Annapolis document, was held up at an Israeli army roadblock for 25 minutes. An angry Qureia said he and the other negotiators returned home because of the humiliation. "We will propose never to conduct negotiations in Israel again," he said.

Israeli Foreign Ministry spokesman Mark Regev said Israel regretted the incident and pledged it would be investigated. He said Foreign Minister Tzipi Livni talked to Qureia, and he hoped their meeting could be rescheduled as soon as possible. "Important work needs to be done, gaps must be narrowed," Regev said.

Briefing ministers at Sunday's weekly Cabinet meeting, military intelligence chief Maj. Gen. Amos Yadlin warned that Hamas could try to foil the forthcoming conference, an official who attended the closed-door meeting said.

"He said he saw Hamas stepping up its efforts to carry out acts of terrorism if Annapolis looks like being a success," the official said, speaking on condition of anonymity according to civil service rules.

At the event in Ramallah, Abbas called for the establishment of an independent Palestinian state on all lands captured by Israel in the 1967 Mideast war, with east Jerusalem as its capital, and said a peace agreement would "achieve security and peace for us and for the Israelis."

Sunday's rally, marking the third anniversary of Arafat's death, was attended by tens of thousands of supporters of Fatah, the group Arafat founded in the 1960s and led until he died in 2004.

The turnout at the annual service was the largest since Arafat's death, in large part because of Fatah's concern about the rise of Hamas.

Hamas forces overran the Gaza Strip in June, defeating Fatah's loyalists in five days of fighting.

Abbas responded by expelling Hamas from the Palestinian government, and has moved cement Fatah's grip on power in the West Bank since then. Many in the crowd at Sunday's rally held yellow Fatah flags, and public schools and government offices -- both seen as Fatah strongholds -- closed early to allow people to attend the memorial.

The crowd overflowed into the streets around the government compound in Ramallah where it was held.

During his 20-minute speech, Abbas credited Arafat with uniting his fractured people. Lacking Arafat's guerrilla-fighter charisma, the soft-spoken Abbas used the rally to emphasize his position as heir to Arafat's mantle.

Abbas also attacked his Hamas rivals, saying the group must "retract its black coup" in Gaza before there can be dialogue between rival Palestinian factions.

Anan Abdeen, 27, said Arafat would have supported the peace moves by Abbas, widely known as Abu Mazen.

"Fatah chose to enter the negotiations with Israel. That was Arafat's decision, and Abu Mazen is following this decision," Abdeen said.

Israelis have mixed views of Arafat. Some recognize him as a pioneer who signed the first Israeli-Palestinian peace agreement in 1993. Arafat won the Nobel Peace Prize in 1994, along with then-Israeli Prime Minister Yitzhak Rabin and Foreign Minister Shimon Peres. But many Israelis hold him responsible for the second Palestinian uprising, which broke out in late 2000 as peace talks were faltering. More than 4,000 Palestinians and 1,000 Israelis have died in violence since then.

In Gaza City on Sunday, Hamas police beat several students who tried to hold an Arafat memorial near their high school, a witness said. Hamas police arrested a teacher at a similar incident elsewhere in central Gaza, a school official said. Both witnesses asked not to be identified, fearing retribution from Hamas forces.

Hamas denied that report.

A rocket fired Sunday by militants in Gaza exploded in a dairy barn at an Israeli border village, killing six cows, residents and the Israeli military said. Palestinians fire rockets at Israel from Gaza almost every day.