Four held over landfill dumping site at Tredegar
Four men have been arrested in connection with investigations into an alleged illegal landfill site in Blaenau Gwent.
Initial investigations estimate more than 20,000 tonnes of waste have been illegally landfilled in Tredegar.
Gwent Police carried out a number of raids on properties at 0830 GMT involving more than 50 officers and Environment Agency Wales officials.
Agency officials are concerned the waste poses a threat to nearby rivers.
Environment Agency Wales says three of the men, aged 43, 42 and 34, were arrested in the Brynmawr area.
A fourth man, aged 44, was arrested in the Tredegar area.
All four, said to be from the heads of the Valleys, are being questioned at Ystrad Mynach police station.