Police have arrested a 19-year-old man and seized from him mephedrone powder worth Rs 18.94 lakh near Mira Road railway station in Thane district, an official said on Wednesday.

Officials of the Anti-Narcotics Cell of the Mira Bhayandar-Vasai Virar police arrested the accused, identified as Sadak Rashid Ansari, a resident of Nalasopara in neighbouring Palghar district, on Tuesday, DCP (Crime) Mahesh Patil said.