The prosecution's decision to detain former president Mohamed Mursi for 15 days pending investigation on charges of espionage arouses suspicion and marks the rule of law's collapse, the National Alliance for Supporting Legitimacy said on Friday.

The Islamist alliance was founded by the Muslim Brotherhood and other Islamist parties.

Detaining Mursi comes at a time when the whole world asks for releasing Mursi who is kidnapped and is not allowed to meet his family or aides, a statement for the alliance said.

Mursi's application for presidential candidacy was looked into before he was elected and there were no charges against him, the statement said.

The timing is a sly attempt to stir Egyptian public opinion so that some would turn today's protests violent, it added.