The United States on Tuesday strongly condemned Egypt's mass death sentencing of more than 500 members and supporters of the outlawed Muslim Brotherhood movement, saying it would be "unconscionable" for Egyptian authorities to carry out the ruling.

State Department Spokeswoman Marie Harf said verdicts handed down on Monday to 529 defendants and the beginning of another mass trial on Tuesday of Brotherhood Supreme Guide Mohamed Badie and 682 others "represent a flagrant disregard for basic standards of justice."

Monday's verdict sparked a chorus of local and international condemnation, with many questioning the fairness of the proceedings that only spanned two days.

The defendants were convicted of murder and other offences during violence that broke out in the central Minya governorate in the aftermath of the forced dispersal of two Cairo protest camps by supporters of deposed president Mohamed Morsi on 14 August.

"Implementation of yesterday’s verdict imposing the death penalty on 529 defendants after a two-day trial would be unconscionable," Harf told a regular press briefing.

"If Egypt's leaders want to ensure a political transition to democracy that ultimately improves the stability and economic prospects of their country and their people, and that's respected by the Egyptian people, they must unequivocally ensure an environment that is free of intimidation or retribution," Harf said. "This includes ensuring due process and fair trials for all Egyptians accused of crimes."

In response to the outcry triggered by the verdict, Egypt's Ministry of Justice stressed in a statement that the Egyptian judiciary is independent, saying the ruling was not final.
A ministry spokesman said that the convicted can appeal the verdict and be granted a retrial.

Harf added that Washington is "currently evaluating our aid policy" toward Egypt, saying it is important that the US maintain its ties with the country "for a variety of security, economic [and] regional reasons."

The US suspended much of its $1.5 billion in military and economic aid to Egypt last year pending progress towards democracy.

"Everything that happens on the ground, including this, will play into the decision about where our assistance relationship goes from here," she said.

"We are re-evaluating that relationship every day. We are determining if this assistance will stay suspended, if more will be suspended, if some will be brought back online," Harf said, adding that the "outrageous, shocking, unconscionable actions" that the Egyptian government is taking will affect the US administration's decision.