CAIRO (Reuters) - Tens of thousands of Egyptians demanding an end to military rule converged on Cairos Tahrir square on Friday in what activists say will be the biggest day yet in a week of demonstrations in which 41 people have been killed. The military men who took over after people power toppled President Hosni Mubarak on February 11 are themselves under fire from protesters who accuse them of clinging to power, leading to street battles that look like a replay of Februarys unrest. The ruling army council named Kamal Ganzouri, 78, who served as prime minister under Mubarak from 1996 to 1999, to head a national salvation government. Prime Minister Essam Sharafs cabinet had resigned this week amid the protests. The United States, long a bedrock supporter of Egypts military, called on the generals to step aside as soon as possible and give real power to the new cabinet immediately. The military rulers say they are working on a transition of power, including parliamentary elections set for Monday, which could be overshadowed if violence continues. Some protesters say the army cannot be trusted to hold a clean vote. Speaking to Reuters by telephone shortly after his appointment was announced, Ganzouri declined to reveal details of his new cabinet. Everything will be outlined later, he said. After his appointment was confirmed, crowds in Tahrir chanted: They brought a thief and appointed another thief, referring to Sharaf and Ganzouri. Say without fear: the (army) council must leave, they shouted. Activists sought to bring a million people into the streets of Cairo on what they dubbed the Friday of the last chance. Thousands flooded into Tahrir Square for prayers, where Sheikh Mazhar Shahin told worshippers the protest would go on until Egypt had a new salvation government. Protesters said they expected the crowd to continue to grow in the afternoon. Friday, the weekly Muslim prayer day, has traditionally been the biggest day of demonstrations in the Arab Spring protests sweeping the Middle East this year. We are all for the revolution and stand steadfast for the demands of the revolution. There is no conflict between us and the army, the cleric said in an address over loudspeakers. Until a truce calmed violence on Thursday, streets around Tahrir had become battle zones with stone-throwing protesters fought police firing tear gas, pellets and rubber bullets. A steady stream of men, women and children surged into Tahrir before Friday prayers. Some, like Atef Sayed, 45, with his wife and two daughters, were protesting for the first time. Were here to back the idea that the military council hands responsibility to civilians and focuses on military affairs. Nine months have gone by with many things that have happened in a way opposite to what the revolutionaries wanted, he said. But enthusiasm for the protests was not universal. About 5,000 people waving Egyptian flags demonstrated in favour of the military rulers in Cairos Abbassiya district. The people want the emptying of the square, shouted the demonstrators. A big banner read: Egypt will not be governed from Tahrir square. Activists who tried to organise a march to Tahrir from a mosque in the capitals Shubra neighborhood were rebuffed. The army council will leave in six months. We have elections in three days. What do these people want? asked one worshipper angrily. They are hired to start trouble. The White House stepped up pressure on Egypts military rulers to speed up the handover to civilian control. Full transfer of power to a civilian government must take place in a just and inclusive manner that responds to the legitimate aspirations of the Egyptian people, as soon as possible, White House spokesman Jay Carney said in a statement. The United States strongly believes that the new Egyptian government must be empowered with real authority immediately. Activists set up checkpoints at entrances to Tahrir square, searching people arriving and checking identity cards. Weve had enough of government controlled by the military, read a huge banner tied between two lamp posts. Several hundred young men marched around waving Egyptian flags and chanting Down, down with military rule and Down, down with the field marshal, a reference to army chief Mohamed Hussein Tantawi. The army, once hailed for its role in easing Mubarak from power, has come under increasing fire for dragging out a handover to civilian rule, even as Egypts economy falters.