SANAA: Vast crowds of Yemenis took to the streets on Friday to demand the immediate departure of President Ali Abdullah Saleh, instead of the phased handover of power envisaged by a Gulf-mediated agreement. Some 100,000 people flooded a five-km stretch of Sana'a's main Siteen Street to mark a “Friday of Loyalty to the Martyrs” - at least 142 protesters have been killed during three months of anti-Saleh unrest across Yemen. “We will continue our revolution forcefully and we will not back down even if we have to offer a million martyrs,” a cleric shouted to crowds, as they released balloons inscribed “Leave!”. Equally large pro-Saleh crowds also gathered in the capital to mark a “Friday of Constitutional Legitimacy”. Waving flags, the demonstrators held pictures of the president and banners reading: “Be firm and don't back down, we are with you.” Opponents of the agreement, due to be signed in Riyadh on Sunday, say the president cannot be trusted to honor it. Tens of thousands of anti-Saleh protesters turned out in other cities, including Ibb, Baydah and Hudaida, where plainclothes gunmen wounded 10 demonstrators, activists said. A government official has said Saleh will sign the GCC-mediated agreement on Saturday in Sanaa, but send Abdel-Karim Al-Iryani, vice president of his ruling party, to the official signing ceremony in Riyadh. The opposition coalition will also sign on Sunday. The agreement would give Saleh and his entourage, including relatives who run branches of the security forces, immunity from prosecution. The president would have 30 days to resign. He would appoint a prime minister from the opposition to head a transitional government until a presidential election 60 days later.