Egypt's main opposition says it will appeal the result of the constitutional referendum, claiming electoral fraud and widespread violations.
Initial results from the final round of voting on Saturday show 63 percent of voters back the charter.
National Salvation Front spokesman Amr Hamzawy is calling for an investigation:
"We do not consider that constitution as a legitimate constitution. It violates our basic rights, social and economic before civil and personal rights. It violates our interests and the popular interest in building a socially just society and a democratic system. And we will continue to attempt to bring down the constitution peacefully and democratically."
Following the result, President Mursi has appointed 90 new members to the upper house of parliament, saying they are mostly liberals and non-Islamists.