Schoolchildren in Chirk kept indoors during Kronospan fire

School staff at Ysgol y Waun, which sits about 300 metres from the gates of the factory, say they have taken advice from environmental health experts and decided not to allow the pupils to go outside for breaks and over lunchtime.

The fire, which broke out in the early hours of Monday, continues to burn at the firm's log yard on its complex in the centre of Chirk.

North Wales Fire and Rescue Service said that firefighters remained on site throughout the day yesterday .

"Crews are working with staff on site and we expect them to remain on site throughout the day," a spokesman for the fire service said.

The decision to keep children inside at Ysgol y Waun was announced in a joint statement from head, Mr John Roberts and chair of governors, Mr Frank Hemmings.

"We have taken advice from the Environmental Health/ Housing Team and the Local Authority Health & Safety team regarding the fire that is burning in the Kronospan Log yard.

"The fires, even when extinguished, are expected to continue to produce smoke for up to four days," they said.

Coverage so far:

• Emergency council meeting called as Kronospan fire in Chirk enters third day

• 'There is a serious risk to people's lives': Concern after string of fires at factory

• Chirk residents urged to close windows and doors as Kronospan fire rages on

• Fire continues to rage at Kronospan factory in Chirk as company promises 'full enquiry'

• Firefighters spend 12 hours battling Kronospan factory blaze in Chirk

They said that the changing wind direction will determine which parts of Chirk are affected.

"As a precaution we have taken the decision to keep pupils indoors today and tomorrow and to review the situation on Friday morning."

Wrexham County Borough has urged residents to take advice from Public Health Wales.

It says: “If you are in a place affected by smoke, stay indoors and keep doors and windows closed when affected by the smoke, but open them again to air your home when the smoke passes. If you need to be outdoors, avoid areas affected by smoke or ash, or limit the time you spend in them. Motorists who have travel through the smoke should keep windows closed, turn off air conditioning and keep their air vents closed."

The public health advice goes on to say that smoke can irritate airways, the skin and the eyes leading to coughing and wheezing, breathlessness and chest pain.

"This can also mean that problems such as asthma get worse; people with asthma should carry their inhaler with them at all times."

Chirk Town Council has called an extraordinary meeting for tonight .