Oily slicks of kerosene still appeared to be leaking into the River Taff this week, several days after a breach of thousands of litres was spotted by members of the public.

The breach into the Welsh river was identified last Friday, after people reported strong chemical odours emanating from it. Natural Resources Wales (NRW) officers arrived on site soon afterwards to identify the source of the pollution and were assisted by the south Wales fire and rescue service, which placed absorbent mats and booms to contain as much kerosene as possible.

Residents along the Taff were advised to keep windows and doors closed last week, after it emerged that thousands of litres of kerosene from a GE Aerospace site in Nantgarw, Rhondda Cynon Taf had entered the river. Four kilometres (2.5 miles) of waterway were affected, according to NRW.

NRW was unable to confirm what quantity of kerosene entered the river.…