On the two-year anniversary of Egypt's uprisings -- teargas and smoke permeate Cairo's Tahrir Square.

Police and demonstrators clashed there through the early morning as Egyptians gather in the iconic square, considered the heart of the uprisings that swept former President Hosni Mubarak from power.

Protesters now, opposed to President Mohamed Mursi, aim to revive the demands of a revolution that they say has been betrayed by the president and his Islamist allies, the Muslim Brotherhood.

(SOUNDBITE)(Arabic) DEMONSTRATOR, WAEL IBRAHIM, SAYING:

"This is our revolution, not a revolution of destruction. We will retrieve our revolution to make Egypt and the next generations happy. Our demands are: dignity, humanity and proper salary, we do not need to live in villas."

Mursi faces discontent on multiple fronts.

His opponents say he and his group are seeking to dominate the post-Mubarak order.

But the Brotherhood dismisses such criticism as unfair.

It accuses its opponents of failing to respect the rules of the new democracy that put the Islamists in the driver's seat through elections.

The Brotherhood has decided against mobilising in the street for the occasion -- a decision that could reduce the likelihood of confrontation with opposition activists.