National Intelligence Service chief Ko Young-koo says the latest satellite photographs have failed to shed new light on the cause of a massive explosion in North Korea last week.

In a closed door briefing to members of the National Assembly's intelligence committee, Ko reportedly said photographs taken around the Yanggang Province via a U.S. commercial satellite showed no traces of manipulated detonation.

Ko said the Seoul government will continue to work with the United States to look into the cause of the explosion.