Caereinion High School is on the same campus as the primary

Llanfair Caereinion primary, near Welshpool, shares a campus with Caereinion High School, where more than a third of the children are unwell.

Pupils at both schools, have fallen ill with a suspected "viral infection", according to Powys Council.

Symptoms include gastric upsets, high temperatures and headaches.

Environmental health officials said illnesses at both schools seemed to be linked because the pattern of symptoms were the same.

The illness at Caereinion High spread quickly to infect many of its 563 students. The first cases were reported last week.

On Thursday, primary school head teacher Rhona Evans said parents of 30 of her 186 pupils had phoned the school to say their children were now ill. Some have brothers and sisters at the high school.

Flu-like symptoms

Ms Evans said the "flu-like" symptoms affecting her pupils had to be connected with the bug at the high school.

Tests are being carried out there by environmental health officials to try to identify the source of the infection at the high school.

Meanwhile, leaflets have been sent home to advise parents with children at both schools about the illness. Advice includes keeping children at home 48 hours after symptoms have cleared up.

On Wednesday, the high school said it had "turned the corner".

Powys Council said early indications showed that a viral infection had led to the illness at the high school but it was "yet to be confirmed".