CAIRO: Tens of thousands packed Cairo's Tahrir Square on Friday as Islamic activists flexed their political muscle in perhaps Egypt's largest protest since a revolt overthrew president Hosni Mubarak in February.

Islamic activists from across the country flocked into the central square to defend what they called “Egypt's Islamic identity” and to demand that parliamentary elections take place as scheduled by the end of the year.

The rally, organised by hardline Salafi groups and the influential Muslim Brotherhood movement, came as tensions grow between secular activists and the military on the one hand, and Islamic groups on the other.

“The people demand the application of God's law,” thousands chanted under the searing sun, many of them carrying umbrellas or pouring water on their heads to counter the heat.

The rally was officially to start after the Muslim noon prayer, but thousands had already made their way to the square overnight and by morning chants calling for an “Islamic state” rang across Tahrir.

Islamic groups have been organising the rally for weeks, sparking fears of clashes with secular anti-military protesters who have been camped out in the square since July 8.

After two days of meetings, the secular and Islamic groups agreed to try to put their differences aside and focus on the common goals in order to save the revolution that toppled Mubarak, organisers said.

But in a sign of tensions, several hundred protesters stampeded out of the square, screaming and causing momentary panic, only to return later and discover that nothing had happened.

“Don't worry, people were just chanting Allahu Akbar (God is greatest),” said one demonstrator, explaining that the fervour of the chant may have scared people into thinking something had happened.

On the podiums set up around the square, speakers called for unity and partnership, but the protesters chanted Islamic slogans.

Liberal activists such as Mohamed ElBaradei, the former UN nuclear watchdog chief turned anti-Mubarak dissident, want the military rulers to accept a declaration of guiding principles for a new constitution.

The Islamic groups fear that such a document, which the military has said it would be willing to accept, might threaten the second article in Egypt's old constitution, which says Islamic law is the main source of law.

Secular groups feared that an early election would benefit the well-entrenched Muslim Brotherhood, which would then have too much influence in drawing up the new constitution.