Coronavirus: Water issues keep five Blaenau Gwent schools closed
Five schools in Blaenau Gwent are unable to reopen as planned because of issues with their water supplies.
Wales' schools are reopening on Monday.
But Brynmawr Foundation School, Blaen-y-Cwm Primary School in Brynmawr and Ystruth Primary School in Blaina will stay closed for two weeks after "a localised contamination" was found, the council said.
Water supply issues were also found at Tredegar Comprehensive and Willowtown Primary School in Ebbw Vale.
The council said it was hoped the schools could open some time next week.
Where contamination is suspected, water cannot be used until chlorination and re-testing has been carried out and it is deemed satisfactory.
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Councillor Joanne Collins, the council's executive member for education, said: "This is disappointing for the pupils who planned to return next week and their families, but the safety and wellbeing of all our pupils and school staff is always the top priority.
"Our health and safety and environmental health teams are working closely with all the schools affected to resolve the issues as quickly as possible however this is also reliant on some external factors, such as laboratory testing.
"We have been in touch with parents via the schools and will continue to communicate with them when we have further updates."
Tredegar Comprehensive School tweeted it had received a letter from the council at 14:00 BST on Friday informing them of the issue.
It said it was "deeply disappointed" by the news.
A Welsh Government spokesman said: "We have contacted all local authorities about this situation and about ensuring all necessary health and safety checks and tests are completed before schools can be reopened."
A Public Health Wales spokesman said it was not involved in the routine health and safety checks and was "not aware of any risk to the population associated with these tests at the present time".