Women enveloped in black from head to toe, their faces covered except for a narrow slit for their eyes, have become an increasingly familiar sight on Egyptian streets – much to the alarm of a government determined to fight the spread of extremist Islam.

Most Egyptian women wear the hijab, or the Islamic headscarf that covers the hair and neck. But a growing minority is opting for the niqab, or face veil – a form of dress associated more with the puritan Salafi traditions of Saudi Arabia rather than with local standards of religious modesty.