United Nations Secretary-General Ban Ki-moon is "deeply concerned" that former Egyptian President Mohamed Morsi and more than 90 other people were sentenced to death on Tuesday over a mass jail break during the country's 2011 uprising.

"The United Nations is against the use of the death penalty in all circumstances," Ban's press office said in a statement, Reuters reported Tuesday.

"The Secretary-General is concerned that such verdicts, handed down after mass trials, may well have a negative impact on the prospects for long-term stability in Egypt."

The White House has also branded Egypt's sentencing of former Morsi as politically motivated Tuesday, in a sharp rebuke of its uneasy military ally.