US state department official says mass trials and sentences are "inconsistent with Egypt's international obligations".
The United States has expressed "deep concern" after an Egyptian court sentenced deposed President Mohamed Morsi and more than 100 others to death for their role in a mass jailbreak
during the 2011 uprising.
"We have consistently spoken out against the practice of mass trials and sentences, which are conducted in a manner that is inconsistent with Egypt's international obligations and the rule of law," an unnamed state department official said on Sunday.
Noting that they were preliminary sentences, the official added: "We continue to stress the need for due process and individualised judicial processes for all Egyptians in the interests of justice."
The court's verdict on Saturday has already prompted immediate condemnations from Amnesty International and the Turkish president.
Many of those sentenced on Saturday were tried in absentia.
The sentences are subject to legal appeal and the court will pronounce its final decision on June 2, since under Egyptian law, death sentences are referred to the grand mufti, the government's interpreter of Islamic law.
Egypt remains one of Washington's closest security allies in the Middle East. Relations cooled after
Morsi was overthrown by the military nearly two years ago, but ties with Abdel Fattah el-Sisi, his successor, have steadily improved.
In late March, US President Barack Obama lifted a hold on a supply of arms to Cairo, authorising deliveries of US weapons valued at over $1.3bn.