Under Secretary of State Bill Burns, the first senior US official to visit since the July 3 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 fresh elections, but Morsi's Muslim Brotherhood defiantly insists on his reinstatement.
In his talks with interim military and civilian leaders, Burns was to push for "an end to all violence and a transition leading to an inclusive, democratically elected civilian government," the State Department said.
International concern is mounting over the continued detention of Morsi, who has been in custody since hours after the July 3 coup and was quizzed by prosecutors on Sunday over complaints of possible criminal offences.
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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 Brotherhood has refused to join the new government headed by caretaker prime minister Hazem al-Beblawi, who remains locked in talks on a cabinet line-up he says will be dominated by technocrats.
The ultra-conservative Islamist party Al-Nur also confirmed it will not join the interim government. Spokesman Nader Bakkar told AFP: "We would participate only in an elected government."
Beblawi is expected to unveil his full cabinet on Tuesday or Wednesday.
His priorities include restoring security and preparing for parliamentary and presidential elections, which interim president Adly Mansour has side could be held by early next year.
The assets freeze against nine senior Brotherhood figures is part of an investigation ordered by chief prosecutor Hisham Barakat.