Rouhani: Plane incident 'unforgivable error'

He said Iran will punish "all those responsible" and added that the "tragic event" would be investigated properly.

"Iranian armed forces admitting their mistake is a good first step ... We should assure people that it will not happen again," he said, adding that his government was "accountable to Iranian and other nations who lost lives in the plane crash.

Iran's judiciary have arrested some for their role in the crash, judiciary spokesman Gholamhossein Esmaili said on Tuesday (January 14).