CAIRO - Egyptian pro-democracy campaigners called for a new uprising on Sunday, enraged that a court had spared former leader Hosni Mubarak his life over the killing of protesters during the street revolt that ended his three-decade rule. In the first judicial reckoning of a leader toppled in last year's Arab spring uprisings, Mubarak was handed a life prison sentence. His sons were found innocent of corruption charges and senior policemen were acquitted. Thousands took to the streets for protests that went on through the night in Cairo's Tahrir Square and in other cities, adding to political tension building since Mubarak's last prime minister made it through to a presidential election run-off. Many took the verdicts as proof the Mubarak clan still holds sway as Egypt prepares for the vote on June 16 and 17, billed as the final stage of an army-led transition to democracy. "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." Many of the young liberal and left-wing revolutionaries who led last year's uprising were dismayed when their own candidates lost the first round of a presidential election last month. The run-off 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. Suspicion is widespread that the military, led by Mubarak's old defence minister, will still wield heavy influence after the new president takes office. The electoral success of Shafiq, a former air force commander, has deepened those fears. Egypt has been led by army officers since the king was overthrown in 1952. On Sunday morning, a few hundred protesters gathered in Tahrir Square -- focal point of the January 2011 revolt that brought down longtime U.S. ally Mubarak - vowing to stay until there was justice for those killed in the uprising. "Yesterday people were united like in the early days of the revolution. I felt the revolution is returning," 46-year-old engineer Osama Awad in Tahrir said. He said Mubarak must be tried again because key evidence had been concealed and Egyptians must unite against Shafiq. "When Mursi wins, we can re-try Mubarak and the old regime," Awad said. 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. Shafiq has taken a tough stance on law and order, appealing to many Egyptians tired of political chaos and insecurity that have damaged the economy and worsened poverty. Critics say he also has the backing of the powerful army. 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. Mursi, who has been struggling to rally the support of candidates defeated in the first-round, met with Sabahy and another defeated candidate, Islamist Abdel Moneim Abol Fotouh, on Saturday night for a closed-door meeting, according to people who attended the gathering. Sabahy and Abol Fotouh, who was ejected from the Brotherhood last year and has campaigned on a more moderate political platform, came third and fourth in the May 23-24 vote and have refused to throw their weight behind Mursi. "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.