Several hundred protesters have clashed with riot police in Cairo's Tahrir Square, defying Egypt's military rulers who are eager to prevent any demonstrations there since forcefully clearing a weeks-long sit-in by youth activists last week.

Protesters briefly threw bottles and stones at the columns of officers in riot gear before other demonstrators formed a human chain in front of the police to stop the violence.

The rally was planned by youth activists and Sufis, a mystical order of Islam which has generally stayed out of politics.

The protest is a counterpoint to a mass demonstration by hard-line Salafi Muslims last month who called for the imposition of Islamic law.

Egypt's army is eager to prevent rallies in Tahrir Square because activists have used the protests to pressure the military.