The legal adviser of the Freedom and Justice Party, the Brotherhood's political arm, said the court rulings were "political," lamenting the outgoing legislature as the country's "only legitimate and elected body."
"They are hoping to hand it over to Ahmed Shafiq and make him the only legal authority in the absence of parliament. The people will not accept this and we will isolate the toppled regime," Mukhtar el-Ashry said in a posting on the party's website.
A moderate Islamist and a former presidential candidate, Abdel-Moneim Abolfotoh, said the rulings amounted to a "coup" and warned that the youth, pro-democracy groups that engineered the uprising that toppled Mubarak last year would protest the court's rulings.
"Those who believe that the millions of young people will let this pass are fooling themselves," he wrote on his Twitter account.