Hamas members were prominent at the funeral
Tens of thousands of Palestinians in Gaza have taken part in a mass funeral for 12 people killed in an Israeli raid on Thursday.
Militants fired into the air and mourners shouted slogans hostile to new Palestinian Prime Minister Mahmoud Abbas - also known as Abu Mazen.
The funeral comes two days after he was sworn in.
Abu Mazen - a moderate - has criticised radical groups and expressed support for the so-called roadmap to peace drafted by foreign mediators.
Friday's funeral procession - which stretched about three kilometres (2 miles) through Gaza City - was described by the Associated Press news agency as the biggest show of force by militants in nearly a year.
Some fired rifles into the air, as mourners chanted "No to Abu Mazen".
Supporters of the militant group Hamas, using loudspeakers, shouted slogans such as: "Our men will strike Israeli cities" and "Revenge is coming soon".
Palestinians say half the victims were civilians
Witnesses of Thursday's Israeli incursion say six civilians - including a two year-old boy - were among those killed in a 15-hour gun-battle.
The raid was launched a day after a suicide bomber killed three Israelis outside a cafe in Tel Aviv.
Hamas and another group, the al-Aqsa Martyrs' Brigades - an offshoot of Abu Mazen's Fatah faction - said they had jointly carried out the attack.
Observers say the surge in violence in the 31-month-old Palestinian uprising is a blow to efforts by the Quartet - the United States, Russia, the United Nations and the European Union - to bring peace to the region.
The roadmap drafted by the Quartet calls for the creation of a Palestinian state as early as 2005.
It initially requires Palestinians to crack down on militants and the Israelis to start removing their restrictions on Palestinian life.
Hamas leader Ahmed Yassin attended the funeral under heavy guard
Hamas has rejected the plan. The Israelis have cautiously welcomed it, but they would only withdraw from Palestinian areas once the new Palestinian government has reined in the militants.
US Secretary of State Colin Powell - who is on a tour of Europe and the Middle East - is expected to hold talks with both Palestinian and Israeli leaders next week.
On Thursday, he urged both sides to put aside their differences and start implementing the roadmap.
Mr Powell said Palestinian attacks and Israeli military retaliation should not be allowed to "contaminate" the peace process.