UN Secretary-General Ban Ki-moon expressed serious concern on Monday after an Egyptian court sentenced ousted president Mohamed Morsi to death.
Morsi was among more than 100 defendants given the death penalty Saturday for their role in a mass jailbreak during the 2011 uprising.
"The secretary-general understands that the verdict is still subject to an appeal," said UN spokesman Farhan Haq.
"He will continue to monitor the process very closely."
Ban reaffirmed the United Nations position against capital punishment.
The UN chief also "underscored the importance of all parties taking steps to promote - and avoiding those that could further undermine - peace, stability and the rule of law in the region."
The United States and the European Union also expressed concern after the verdict was announced against Morsi, the Islamist president who held office for a year until he was ousted in 2013.
*The story was edited by Ahram Online