The ancient Christian community of the northern Iraqi city of Mosul had all but fled by Saturday, ending a presence stretching back nearly two millennia after radical Islamists set them a midday deadline to submit to Islamic rule or leave.

The ultimatum by the Islamic State in Syria and the Levant (ISIL) drove out the few hundred Christians who had stayed on when the group's hard-line Sunni Muslim fighters overran Mosul a month ago, threatening Christians and the diverse city's other religious communities.

Last week the Islamic State, as ISIL has taken to calling itself, gave any remaining Christians a final choice to make by Saturday noon: convert to Islam, pay a religious tax, or face the sword.