Natural Resources Wales (NRW) can confirm that thousands of fish have been killed due to a major pollution incident in the River Clywedog near Wrexham.
Officers from NRW have been on site investigating since the incident happened on Tuesday night (4 September).
NRW has also identified the probable source of the pollution, but this cannot currently be confirmed for legal reasons.
A stretch of about nine kilometres of the river has been affected, leading to a massive loss of fish - mainly brown trout but also bullhead, lamprey, stoneloach, salmon parr, chub, eel, bullhead, stickleback, perch and minnow.
Anthony Randles, Natural Resource Management Team Leader from NRW, said:
“Protecting Wales’ rivers and their wildlife is one of our most important jobs, and we deal with pollution incidents as a matter of emergency.
“Our officers are still on site collecting water samples for analysis and assessing the scale of the impact on fish and river life.
“We will continue to investigate how this happened and gather evidence to take enforcement action if required.”
If you see any incidents of pollution or fish in distress please report it to our incident hot line on 0300 065 3000.