The head of London's Strictly Orthodox rabbinate has warned schools and community groups to take proper precautions for educational trips following the rescue of a group of Charedi youth on the Kent coast last month.

Rabbi Ephraim Padwa wrote to say that health and safety rules must "always be adhered to" and appropriate preparations made for outings.

Rabbi Padwa, head of the rabbinate of the Union of Orthodox Hebrew Congregations, asked that "all those responsible for the welfare of our young are acquainted with the appropriate rules and abide by them".

A group of 34 teenagers along with two adults from the Ahvas Yisroel Community Centre in Stamford Hill had to be rescued by lifeboats after they had become stranded by the rising tide during a coastal walk near Dover harbour.

Hackney Council is currently conducting an investigation into last month's incident, which a spokeswoman said that it regarded with "grave concern". The community centre is located in the London borough.

One question the council wants to resolve is whether there is any link between the Ahvas Yisroel group, which is associated with the Vishnitz Chasidic sect, and an unregistered Vishnitz yeshivah, called Chaim Meirim.

The council understands that some of the rescued boys mentioned that they came from Chaim Meirim. It also understands the trip to have been booked under that name.

Asked if either of the adults on the Kent trip was associated with any of the Chaim Meirim institutions, a spokesman for the Ahvas Yisroel group said that he had no other information other than that they were "volunteers at the Ahvas Yisroel community centre".

Local yeshivot have come under increasing scrutiny from the education authorities because it is illegal to operate a school for children under 16 if it is not registered.

But a legal argument put to the Department for Education on behalf of one Stamford Hill institution has contended that a yeshivah does not count as a school for the purposes of the law.