Egypt crisis: Fears of failure for foreign mediation
International mediators have expressed fears attempts to solve Egypt's crisis may fail, with one US senator warning it could be "days from bloodshed," BBC reported.
John McCain and fellow senator Lindsey Graham urged the military-backed government to free political prisoners.
They also urged talks with the Muslim Brotherhood of Mohammed Morsi, who was ousted by the military on 3 July.
But acting President Adly Mansour warned against "unacceptable interference in internal affairs."
The Brotherhood has also criticised the US senators.
Envoys from the European Union, Qatar and the United Arab Emirates are also in the country trying to resolve the crisis.
Fears are growing that the army will move in to break up two pro-Morsi sit-ins in Cairo, triggering further violence and bloodshed.
Egypt has been in turmoil since Mr Morsi - Egypt's first freely elected president - was overthrown last month following mass demonstrations against him. He is being detained at an undisclosed location.