The development sets the stage for a possible confrontation between the military-backed government and the thousands gathered at the protest sites in support of ex-President Mohammed Morsi.
The protesters have said they will not leave until Morsi, ousted in a popularly supported coup on July 3, is reinstated.
Weeks of efforts by the international community to end the standoff and find a peaceful resolution have so far failed. Egypt's interim prime minister warned just ahead of the Muslim Eid al-Fitr holiday that ended yesterday that the government's decision to clear the sit-ins was "irreversible."
At the main Cairo sit-in, vendors said they have sold hundreds of gas masks, goggles and gloves to protesters readying for police tear gas. Three waist-high barriers of concrete and wood have been built against armored vehicles.
The security officials said they would set up cordons around the protest sites to bar anyone from entering, and one of the officials said that could begin as soon as sunrise. But by dawn today, there was no indication of any troops moving and the government has not confirmed when forces would advance on the sit-ins.
Interior Ministry officials, speaking to The Associated Press on condition of anonymity because they are not authorized to discuss details of the security plans, said they are prepared for clashes that might be set off by the cordons. The officials said police are working with the Health Ministry to ensure ambulances are on hand for the wounded and that armored police vans are nearby to take away those arrested.
A special force within the riot police trained for crowd dispersal is expected to deal with protesters. In the past, however, Egypt's riot police, many lacking the training to deal with unarmed civilians, have resorted to using lethal force.
