The second-most senior U.S. diplomat has met with the imprisoned deputy leader of the Muslim Brotherhood, according to a senior official, a sign that the United States is ramping up its attempts to mediate Egypt's political crisis.
U.S. Deputy Secretary of State Bill Burns traveled late Sunday night to the notorious Tora Prison, a jail in the middle of Cairo that has housed some of Egypt's most famous prisoners, to meet with Khairat el-Shater, the official said.
The Brotherhood had claimed until now that El-Shater refused to meet.
El-Shater, one of the country's wealthiest businessmen, is highly influential within the Brotherhood and the organization's main financial backer. After the military overthrew the government last month, el-Shater was detained along with hundreds of Brotherhood supporters as part of the military's crackdown on the Islamist group.
The meeting, which took place in the same prison where former President Hosni Mubarak is serving out a life sentence, lasted 90 minutes and, while there were no breakthroughs, it was "productive," according to the senior official.
Burns is one member of a "quartet" of diplomats trying to negotiate with the Egyptian military and Brotherhood. EU envoy Bernadino Leon and the foreign ministers of Qatar and the United Arab Emirates also met with el-Shater.
"There seems to be a window where the two different parties of the conflict are allowing for new mediation efforts," H.A. Hellyer, an expert on Egypt at the Brookings Institution, said. "That's a change."
The Brotherhood had strongly denied the meeting took place, an apparent attempt to keep any mediation efforts under wraps. Publicly, the group says it is not negotiating and will end its protests if Mohamed Mosi is reinstated as president.
After ABC News initially posted news of the meeting on Twitter, a Brotherhood spokesman called an ABC News reporter and acknowledged that el-Shater met Burns, but called it a "swift exchange" that lasted only 10 minutes.
"It was not a real meeting," Gehad el-Haddad told ABC News.
The United States is furiously mediating between the military and Brotherhood, trying to help Egypt stabilize after the military takeover a month ago. Egypt has long been the United States' most important Arab ally, and U.S. officials are eager to see the military avoid any steps that could lead to civil war.
On two occasions in the past month, the Brotherhood says, soldiers opened fire on crowds, killing more than 140 people. After the latest incident, the United States faced heavy pressure to cut the $1.3 billion in military aid and $250 million of humanitarian assistance, something the White House has strongly resisted.
The United States has sent not only its second-highest diplomat to Egypt, but President Obama dispatched Sens. John McCain, R-Ariz., and Lindsey Graham, R-S.C., to Cairo.
The heavy U.S. mediation attempts have drawn a strong rebuke from the head of the military.
Gen. Abdel Fattah el-Sissi, considered the most powerful man in Egypt, told the Washington Post in a rare interview that the United States has not providing enough support, despite the threat of civil war.
"You left the Egyptians. You turned your back on the Egyptians, and they won't forget that," said el-Sissi, whom the paper described as "indignant."
"Now you want to continue turning your backs on Egyptians?"
On the one hand, Sissi's comments show how the United States has alienated both sides in a country that is increasingly polarized. El-Haddad, the Brotherhood spokesman, has said the United States "failed to stand up for principles" and had approved overthrowing Morsi, who was the country's first democratically elected president.
On the other hand, however, the military has restrained itself in the past week, choosing not to break up the sit-ins forcibly, as many feared. It's unclear why it hasn't, but the United States has been applying considerable diplomatic pressure, including almost daily calls between el-Sissi and U.S. Secretary of Defense Chuck Hagel.
That pressure continues daily in Cairo: Burns' trip has no end date. Burns, McCain, and Graham are meeting with senior officials in the Egyptian military, as well as in the Brotherhood, but have no public plans to meet with the former president.
To date, EU foreign policy chief Catherine Ashton is the only foreign official to have met with Morsi at an undisclosed location. She described last week's meeting as "friendly, open and frank."
Before contacting ABC News, el-Haddad took to Twitter to call stories about el-Shater's meeting with Burns "fictional." He said el-Shater walked out as soon as he saw the participants.
"I'm not in any position to speak. Morsi holds the key to solving your mess. Go talk to him," el-Hadded tweeted, quoting el-Shater and using shorthand. "There is no alternative to constitutional legitimacy."
But the meeting suggests that the Brotherhood realizes it must deal with the United States, if only because of the influence the United States seems to have on the Egyptian military.
"The Muslim Brotherhood have come around to the notion that they don't have the support to bring back Morsi," Brookings' Hellyer said. "They realize they have nowhere else to turn."