FILE PHOTO - Iranian President Hassan Rouhani attends a meeting with Russian President Vladimir Putin on the sidelines of a session of the Supreme Eurasian Economic Council In Yerevan, Armenia October 1, 2019. Sputnik/Alexei Druzhinin/Kremlin via REUTERS

DUBAI (Reuters) - Iran will punish all those responsible for the accidental shooting down of a Ukrainian passenger plane, President Hassan Rouhani said in a televised speech on Tuesday, adding that the “tragic event” would be investigated thoroughly.

“It was an unforgivable error ... one person cannot be solely responsible for the plane crash,” he said.

“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”.