TOKYO, Oct 16 (Reuters) - Japan's government has decided to release treated water containing radioactive substances from the Fukushima Daiichi nuclear plant into the sea, Jiji news agency and other media reported on Friday.

A formal decision is expected to be made within this month, the reports said.

Tokyo Electric has collected more than a million tonnes of contaminated water since the plant was crippled by an earthquake and tsunami in 2011. (Reporting by Kaori Kaneko; Editing by Muralikumar Anantharaman)