CAIRO Egyptians demonstrated throughout the night in Cairo's central Tahrir Square and other cities, enraged that a court had spared deposed leader Hosni Mubarak his life over the killing of protesters in the uprising that ended his three-decade rule.
Many wanted death for Mubarak, who was handed a life prison sentence on Saturday.
They saw the sentence and the acquittal of senior police officers as proof that the old regime still wields influence and feared Mubarak could now be acquitted on appeal.
Some demanded that the country's presidential election be cancelled.
Thousands of people poured onto the streets on Saturday after the verdict. By Sunday morning, a few hundred were still gathered in Tahrir Square -- focal point of the January 2011 uprising that brought down the longtime U.S. ally - and said they would stay until those killed in the uprising were avenged.
"This was not a fair verdict and there is mass rejection of the judge's ruling," said one protester, Amr Magdy. "Tahrir will fill up again with protesters. In Egypt the only way you can get any justice is by protesting because all the institutions are still controlled by Mubarak figures."
The long-awaited Mubarak verdict deepened fear among many pro-democracy campaigners that recent developments are reversing Egypt's emergence from decades of autocratic rule.
Many of the young liberal and left-wing revolutionaries who began the uprising were dismayed when their own candidates lost the first round of the presidential election last month.
The vote is seen as the last step in a transition from military rule to civilian government.
A run-off on June 16 and 17 will pit Mubarak's last prime minister Ahmed Shafiq, who holds Mubarak as a role model, against the candidate of the socially conservative Muslim Brotherhood, Mohamed Mursi.
Dozens of young men ransacked Shafiq's campaign office in Fayoum south of Cairo overnight, the second such attack in recent days, state news website al-Ahram reported. A Shafiq campaigner in Cairo said he was not aware of the attack.
Footage posted on Al-Ahram's website showed youths destroying and burning Shafiq's pictures and banners and others chanting: "Fayoum says Ahmed Shafiq is feloul," an Arabic word used to refer to remnants of the Mubarak era.
Leftist Hamdeen Sabahy, who failed to progress to the election run-off, joined thousands of protesters in Tahrir late on Saturday. The Brotherhood's Mursi also toured the square.
"We are in disbelief that either Shafiq or Mursi could be president," said Ahmed Abdulla, 21, one of hundreds of hard-core football fans who have taken part in sporadic street protests since Mubarak was toppled.
Mursi, who has been struggling to rally the support of candidates defeated in the first-round vote, met with Sabahy and another defeated candidate, Islamist Abdel Moneim Abol Fotouh, late on Saturday for a closed-door meeting, according to people who attended the gathering.
"The situation now is deadlocked but one scenario would be to stop the second round from happening," said a political activist who witnessed the meeting.
"We plan to call for marches on Monday, Wednesday and a big million-man march on Friday," the activist said.
(Additional reporting by Omar Fahmy, Yasmine Saleh and Mohamed Abdallah; Writing by Tom Pfeiffer; Editing by Angus MacSwan)