SHAFAQNA – The Grand Ayatollah Makarem Shirazi answered a question about a woman without Hijab leading mixed congregational prayer.
Question: In one of European cities, there is a Mosque where a congregational prayer (Salaat Jama’ah/Jama’at) is held in there, and the prayer leader is a woman without Hijab; and men and women mixed together pray behind her. What is the ruling of Islam in regard to this act?
The Grand Ayatollah Makarem: This act is Haram in many respects, and it must be said to them that such prayer is definitely void (Batel); and there is also this possibility that some of those opposing Islam, in order to weaken Islamic decrees/Islamic Laws, bring to existence such scenes and broadcast it in media.
Source: PERSIAN SHAFAQNA