A UK secondary school has been forced to temporarily close after more than 250 pupils and staff members fell victim to a "flu like illness" that spread rapidly.

In an email seen by the BBC, Lee Jarvis, the head teacher at St Martin's School in Caerphilly confirmed the school had experienced "a significant outbreak" of the mystery bug.

Mr Jarvis told parents and carers that the school would be shutting for a short "firebreak" period that would allow a thorough deep clean to be conducted, with online learning in place.

A total of 242 pupils and 12 members of staff have been reported absent from St Martin's, with symptoms including vomiting, diarrhoea, high temperatures, cough, headaches, fatigue and "general flu-like effects", Mr Jarvis wrote. He said the average recovery time appeared to be about seven days.

The email explained the school would close temporarily to allow time to reduce transmission and complete a deep clean of the building, with the aim of reopening on Tuesday 9 December.

Mr Jarvis went on to say that the closure may go one longer, and that the situation would be monitored and updates issued to families as needed.

Parents were urged to keep children at home and not send them into class if they showed any symptoms at all, "even if mild".

Public Health Wales confirmed it had been in communication with the school, which made the decision to close following its own internal risk assessment which led it to "decide to shut down temporarily".