Sectarian clashes, a dismal feature of Egyptian life for more than a decade, have risen alarmingly.

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There was a large police presence, following Monday's sectarian clashes, and two water canon vehicles arrived.

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Since the 1970s and 1980s - when there was a rise in extremist Islamist thought and Christian radicalism - there have been frequent sectarian clashes in Egypt.

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In Egypt, where the revolution featured heartwarming scenes of cohesion between Muslims and the 10% Coptic Christian minority, sectarian clashes have again erupted, with at least 13 killed in riots on the outskirts of Cairo.

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Violence there flared again on Sunday, with police reporting more sectarian fighting on the streets and clashes between police and youths.

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