The Carter Center, a monitoring group with headquarters in Atlanta, sent observers to Egypt during the presidential election process.
The center released its preliminary findings from its observer mission following a second round of voting for president and administrative moves by the ruling Supreme Council of Armed Forces.
Former U.S. President Jimmy Carter, in a statement, said he was "deeply troubled" by the turn of events in Egypt.
Carter said that constitutional declarations by SCAF violate previous commitments to hand power over to an elected civilian government.
"A constitution is a permanent foundation for the nation, and must be fully inclusive and legitimate," he said. "An unelected military body should not interfere in the constitution drafting process."
SCAF reserved for itself some key administrative duties in post-revolution Egypt as the Muslim Brotherhood gains political power in the country.
Carter, who helped broker a 1970s peace deal between Israel and Egypt, told The New York Times in January that a dominant military authority in post-revolution Egypt was inevitable.
"I don't think the SCAF is going to turn over full responsibility to the civilian government," he said.
SCAF faced widespread criticism over the pace at which it was ushering in post-revolution reforms. Elections were originally planned for mid-2011.