His lawyer said he could be bailed within days, six weeks after the armed forces Mubarak once commanded deposed his elected Islamist successor to spark the bloodiest internal conflict in the modern history of the most populous Arab state.
The army detained President Mohamed Mursi on July 3 after huge protests against him. It has since cracked down on his Muslim Brotherhood. Among hundreds of casualties, dozens of security personnel have died, including 25 policemen killed by suspected Islamists near the border with Israel on Monday.
At 85, Mubarak may have no political future but his release could stir emotions and raise new questions on whether the popular uprising that ended his 30-year rule in February 2011 is leading back simply to a new form of military-backed government.
State television showed the 25 coffins of the slain policemen, draped in Egyptian flags, arrive by plane in Cairo.
"Those Brotherhood terrorists have to be killed now by the hands of decent citizens," said Ayman Mohamed, who was introduced as a cousin of one of the dead, his words underscoring the gaping chasm growing in Egyptian society.
The Brotherhood renounced violence decades ago, denies any links with armed militants, including those in Sinai who have gained strength since Mubarak's overthrow, and disavows attacks on churches that have proliferated in the past week.
The United States, a major provider of military and other aid to Egypt, warned against banning the movement and questioned an official account of how 37 Islamist prisoners died on Sunday.
It also cautioned the army-backed government not to act on a threat to outlaw the 85-year-old Brotherhood, which has deep roots in the provinces amongst Egypt's army of rural poor.
The interior ministry has defended its crackdown on the Brotherhood, accusing Islamist terrorists of undermining Egypt.
"To those who have declared they are stopping aid to Egypt or are waving such a threat, the Arab and Muslim nations are wealthy with their people and resources and will not shy away from offering a helping hand to Egypt," Saudi Foreign Minister Prince Saud al-Faisal said.
Saudi Arabia and other Gulf Arab monarchies, apart from Qatar, have long mistrusted the Brotherhood's political ambitions. Israel is also prodding the West to stick by Egypt's army, citing the need for stability. "Like it or not, the army is the only player that can restore law and order," a senior Israeli official said on Monday.
