Cairo - A senior US official was in Cairo on Monday to press for a return to elected government following Mohammed Morsi's overthrow, as the Islamist leader's supporters and opponents readied rival rallies.
Under Secretary of State Bill Burns, the first senior US official to visit since the 3 July overthrow of Egypt's first freely elected president, flew in as the military-installed caretaker government tightened the screws on Morsi's backers, freezing the assets of 14 top Islamists.
Egypt's new leaders are pushing ahead with a transition plan for an interim government and new elections, but Morsi's Muslim Brotherhood defiantly insists on his reinstatement.
In the Sinai Peninsula, three factory workers were killed in a rocket-propelled grenade attack, medics said, in the latest in a spate of deadly attacks since Morsi's overthrow to hit the sensitive and increasingly lawless region which borders Israel.
Burns, scheduled to hold talks with interim military and civilian leaders, will push for "an end to all violence and a transition leading to an inclusive, democratically elected civilian government," the State Department said.
Release of detainees
International concern is mounting over the continued detention of Morsi, who has been in custody since hours after the 3 July coup and who was quizzed by prosecutors on Sunday over complaints of possible criminal offences.
The US administration has still not decided whether he was the victim of a coup, which would legally require a freeze on some $1.5bn in desperately needed military and economic US assistance to Cairo.
On Sunday, two influential US Republican senators, Lindsey Graham and John McCain, urged the administration to cut the aid in response to the coup.
The same day the European Union's foreign policy chief Catherine Ashton called for a swift return to elected civilian government and the release of political detainees.
The Brotherhood has refused to join the new government headed by caretaker prime minister Hazem al-Beblawi, who is forming his cabinet with an eye on technocrats.
The ultra-conservative Islamist party al-Nur also confirmed it will not join the interim government. Spokesperson Nader Bakkar told AFP: "We would participate only in an elected government".
Among the appointments confirmed on Monday was prominent liberal leader Mohamed ElBaradei, aged 71, who was sworn in as interim vice president for foreign relations.
Beblawi is expected to unveil his full cabinet on Tuesday or Wednesday. His priorities include restoring security and preparing for parliamentary and presidential elections.
The assets freeze against nine senior Brotherhood figures is part of an investigation ordered by chief prosecutor Hisham Barakat.
Those targeted include its leader Mohamed Badie. Also hit are five Islamists from other groups, including ex-militant faction Gamaa Islamiya, which carried out a deadly 1997 attack on tourists in Luxor, judicial sources said.
The investigation relates to four deadly incidents since Morsi's overthrow, including clashes outside an elite army headquarters in Cairo last Monday in which dozens of people, mostly Islamists, were killed.
The assets freeze comes a day after prosecutors received criminal complaints against Morsi, Badie and other senior Islamists, with a view to launching a formal investigation.
The interim leaders say Morsi is being held in a "safe place, for his own safety".
A Brotherhood spokesperson vowed to continue "peaceful" protests until Morsi's reinstatement.
"We have a noble goal, a just cause, for which we are prepared to sacrifice," the spokesman, Ahmed Aref, told AFP.
Another Brotherhood official said protesters plan to march on the Republican Guards headquarters, scene of last Monday's violence.
Interim president Adly Mansour has set a timetable for elections by early next year, following a roadmap drafted by the military.
During his single year of turbulent rule, Morsi was accused of concentrating power in Brotherhood hands, sending the economy into freefall and failing to protect minorities.
But his supporters say his overthrow was an affront to democracy, and the Brotherhood is planning more mass protests on Monday, including at the Republican Guard headquarters.
Counter-demonstrations by Morsi opponents are planned in Tahrir Square, epicentre of the 2011 revolution that ousted veteran strongman Hosni Mubarak, and at the Ittihadiya presidential palace.