Two strictly Orthodox schools are facing action from Hackney Council, which says they are operating without the necessary planning permission.
The council is planning to prosecute Torah V'Yirah, a primary school for nearly 300 boys run by the Satmar Chasidic sect which opened two years ago.
It is also considering further steps against Beis Trana, which opened in 1995 and now teaches around 250 girls aged from three to 16.
A council spokesman stated: "Neither of these properties have permission to be used as a school and they are causing significant disturbance to residents in neighbouring properties."
Hackney had "worked with the owners to try to resolve this but has been left with no choice but to take enforcement action to try to conclude this satisfactorily", the spokesman added. "The approach taken throughout has been consistent with the council's planning policy. In line with this, if an enforcement notice is not complied with, the council will consider prosecution."
The council had served an enforcement notice to Torah V'Yirah last November to stop using its premises at 91 Amhurst Park as a school by January. But there had been no compliance to date.
However, Eli Low, who has been liaising with the council on behalf of Torah V'Yirah, said he was "very surprised" to learn of the threat of prosecution.
"We feel we have a good rapport with the council and are liaising with the planning team. We are confident we can resolve this."
The council said it had served 25 enforcement notices in connection with Beis Trana, whose premises span 186-194 Upper Clapton Road. The problem concerned the "unauthorised use" of some of the properties as a school and the use of portable classrooms and of a garden as a playground.
No one from Beis Trana was available to comment.
A recent Ofsted inspection described the school's education as satisfactory and the girls' spiritual and moral development as outstanding.
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