Egypt's top prosecutor has ordered an investigation into accusations against opposition leaders of incitement to overthrow the regime.
A judge will investigate the report filed last month accusing Mohammed ElBaradei, Nobel Prize winner and former head of the UN nuclear agency, with Amr Moussa, former foreign minister and Hamdeen Sabahi, a former presidential candidate, of inciting the overthrow of Egypt's first elected president, Mohammed Morsi.
The accusations were filed by a lawyer during a political crisis over a series of presidential decrees that granted Mr Morsi and the committee drafting the disputed constitution immunity from judicial oversight. Tensions were fed by deadly clashes between pro- and anti-Morsi demonstrators.
The announcement of the new probe came after the election commission said the constitution passed with a 63.8% "yes" in a referendum. The commission rejected opposition allegations of significant vote fraud.
Turnout of 32.9% of Egypt's nearly 52 million registered voters was lower than most other elections since the uprising nearly two years ago that ousted authoritarian leader Hosni Mubarak.
The opposition had campaigned against it with massive street protests that sometimes turned deadly, arguing that it will usher in Islamic rule in Egypt and restrict freedoms. It has vowed to challenge the referendum results and fight for a share of power in the upcoming parliamentary vote expected within two months.
Mr Morsi said the constitution establishes a new republic as he urged the opposition to join a dialogue to heal rifts and shift the focus to repairing the economy.
Muslim Brotherhood leader Mr Morsi said he acknowledged the "respectable" proportion that voted against the constitution drafted by his Islamist allies, but offered no concrete gestures to an opposition.