The National Green Tribunal, Southern Bench, on Monday directed the Ernakulam District Collector to stop illegal sand mining in Periyar River near Panamkudy Kadavu. The Bench, comprising members Justice P. Jyothimani and Prof.R.Nagendran, granted the interim injunction following an application filed by the Paristhithi Samrakshna Samithi, Okkal, represented by its convener, C.P.Thomas.