The office in al-Bab records the names and addresses of potential brides. Isis insurgents consult the records and then go to the women’s houses to ask for their hands  Reuters

Sunni militants from the Islamic State of Iraq and the Levant (Isis) have opened an office in northern Syria for single women and widows who would like to marry insurgents.

Syrian Observatory for Human Rights said the office in al-Bab, a town northeast of Aleppo city, records the names and addresses of potential wives. Isis insurgents consult the records and then go to the women's houses and ask for their hands.

"[Isis] fighters will come knocking at their door and officially ask for marriage," residents told the Observatory.

Isis – whose insurgence, started in June, sparked violence and instability in Iraq and Syria – also announced it would run a honeymoon service for the militants who get married.

The group said it would drive a bus from Raqa in Syria to Anbar, Iraq, twice a day so that newlywed couples can visit the areas recently conquered by the Sunni Islamists.

Isis became known worldwide after it stormed Iraq's second-largest city of Mosul in June, prompting thousands of civilians to flee.

The group now controls large swathes of Syria and Iraq, where it has established a caliphate, and warned it aims to take control of Baghdad.

Isis has been responsible for atrocities including mass kidnappings and executions of people who refused to observe sharia law.

The group sparked further outcry when it declared in July that adulterers will be stoned to death and families should force girls and women to undergo genital mutilation "to distance them from debauchery and immorality".