By Asma Alsharif
CAIRO (Reuters) - Standing by a brick and sandbag barricade on the edge of a Muslim Brotherhood protest camp in Cairo, chief guard Mohamed Saqr is preparing to resist a threatened attempt by security forces to storm in.
The army-backed government has announced it will clear two Brotherhood encampments soon and on Thursday offered a safe exit to those keeping up a peaceful vigil if they leave voluntarily.
But fears of a deadly showdown between protesters and security forces pervade the Rabaa al-Adawiya camp, which sprang up around a mosque in northeast Cairo after the army deposed Islamist President Mohamed Mursi on July 3.
The Brotherhood faithful have sworn to stay there until Mursi, who is now in custody, is reinstated.
"We are ready, ready to die for legitimacy. An attack can happen any time," Saqr said, standing next to a pile of rocks collected for hurling at anyone trying to break into the camp.
Long sticks and makeshift metal shields were also laid out on the ground - scant defense against the bullets of security forces who killed 80 Brotherhood marchers during clashes in the area on Saturday.
Women and children have been moved deeper into the camp for their own protection.
"We are ready with our bare chests, our children and our wives. Our children are a sacrifice for legitimacy," Saqr said.
The confrontation looms almost a month after the army's overthrow of Mursi, Egypt's first freely elected leader, following huge street protests against him.
The interim government has accused Mursi's supporters of arming themselves and inciting violence. On Wednesday it said it would end the vigils because they threatened national security.
Brotherhood partisans have filled dozens of buckets with sand and put them along the roads and spaces between the tents in Rabaa al-Adawiya, ready to extinguish tear-gas canisters.
Inside the camp, they have stocked up on vinegar and soda to help counter the effects of the gas. Protesters have been trained in first aid, said one named Abdulnasser Muafi, who acknowledged that the security forces were far better equipped.
"We have the basic tools. We are trying to avoid the damage that can happen from their attacks. We will most likely have losses," Muafi said.
The camp, which a few days ago was cluttered with boxes and vendors selling knick-knacks, has been tidied up to allow easier ambulance access, although one roadside stall was still selling T-shirts emblazoned with the words "Project Martyr".
Past the entrance, women were sheltering inside the Rabaa mosque, their children sleeping on prayer mats.
"We are here to return our right, legitimacy, to return Mursi. My family is all here, my sister, her children. We are not afraid. Even the children understand that this is a sacrifice and they know that if they don't sacrifice we won't get what we want," Noura al-Rai said.
But 13-year-old Alaa seemed less assured. Propped on the ground next to her mother, she repeated the protesters' mantra that she was there "to defend legitimacy".
Asked if she was afraid of being hurt, Alaa looked away and said only: "But there are many people here."
(Removes the word army from paragraph 4)
(Reporting by Asma Alsharif; Editing by Angus MacSwan and Alistair Lyon)