CAIRO -- Authorities outlined plans Friday to break up two sit-ins by supporters of deposed President Mohammed Morsi, saying they would set up a cordon around the protest sites, and riot police used tear gas to disperse demonstrators threatening a TV complex.
Morsi backers also showed their defiance, briefly setting up a third camp near the airport, but later folded their tents and left.
The military-backed interim government seeks to end a political stalemate that has paralyzed Egypt and deeply divided the country. Supporters of Mr. Morsi and his Muslim Brotherhood say they will not disperse until he is returned to power.
The second-ranking U.S. diplomat, Deputy Secretary of State William Burns, arrived in the Egyptian capital for talks on the political crisis, as Secretary of State John Kerry warned both sides that "the last thing we want is more violence."
Also Friday, Amnesty International reported cases of alleged killings and torture at the hands of Morsi supporters inside the protest camps, saying one man had his throat cut, and another was stabbed to death.
In southwestern Cairo, police fired tear gas at Morsi supporters who rallied in front of Media City, site of most of Egypt's private TV stations, a security official said. A second official told the state news agency that protesters tried to "obstruct traffic in an attempt to affect work at the complex."
The rally was "a desperate attempt by rioters from the [Islamist] current," Maj. Gen. Abdel-Fattah Othman, an Interior Ministry spokesman, told the private TV station Mehwer. "There was reinforcement from police and army that will not allow any reckless person to get close to the Media City or storm it."
He described the protesters as "brainwashed" to attack broadcasters perceived as secular foes of the Islamists.
The new unrest came as state-controlled TV reported that security forces will establish a cordon within 48 hours around the two main protest sites in Cairo, where thousands have been camped out since before Mr. Morsi was ousted by the military July 3.
The government offered protection and "safe passage" to those willing to leave the two main camps -- a large one outside eastern Cairo's Rabaah al-Adawiya Mosque and a smaller one near Cairo University's main campus in Giza. The leadership had earlier given orders to police to end what it described as "threat to national security" and sources of "citizens' terrorism."
Authorities will let people leave without checking identities or arresting them, but will not allow anyone into the protest camps, the report said. It did not elaborate on next steps, but the government earlier said it will use water cannons and tear gas to disperse the crowds.
Morsi supporters also planned rallies late Friday outside security headquarters near one sit-in site, including the Republican Guard club, where their protest last month turned bloody, and another army building.
The cordon around the protest camps raised the potential for new violence. More than 130 Morsi supporters have been killed and hundreds injured since the military coup. The ouster followed mass demonstrations demanding Mr. Morsi resign after a year in office, saying his policies had failed and he put power in his Islamist group's hands.
Interior Minister Mohammed Ibrahim told a newspaper that police have finalized plans to disperse the sit-ins, and were awaiting prosecutors' orders to start the operation's second phase. He said he awaited National Defense Council consent to measures tied to the operation's final phase, which would use force while trying not to injure anyone.
An Egyptian Foreign Ministry official said Mr. Burns would meet today with interim leadership officials and Muslim Brotherhood representatives and its allies. Brotherhood negotiator Amr Darag, who will meet with Mr. Burns, said in an interview that his group and its allies seek "confidence-building measures" for them to sit at the table with their rivals. Such measures include releasing detained Brotherhood leaders, unfreezing the group's assets, lifting the ban on its TV stations and ending violence against its protests.
It was unclear if Mr. Burns would see Mr. Morsi during his second Cairo visit since the coup. On Monday, top European Union diplomat Catherine Ashton saw Mr. Morsi for two hours at the facility where he is being held by the military. An African Union delegation also briefly met the ousted president a day later.