Thousands of ultraconservative Muslims are rallying in the Egyptian capital, demanding the country's new constitution be based on the rulings of Islamic law, or Shariah.

The Islamists pouring into Cairo's central Tahrir Square are waving black Islamic flags and chanting "God' rule."

Friday's demonstration comes amid a fierce dispute between Islamists and liberals over the wording of Egypt's new constitution, which is currently being drafted.

The controversy is about the role of religion in shaping Egypt's future, following the ouster of Hosni Mubarak's regime in a popular uprising last year and the Islamists' subsequent rise to power.

Ultraconservatives want Shariah and its rulings to be the main source of legislation. Liberals and others fear this will lead to strict interpretations of Islamic law and limit freedoms. [litotes]