Classified documents, allegedly from Iran, reveal secret research into how a cyber attack could be used to sink a cargo ship or blow up a fuel pump at a petrol station.

The internal files, obtained by Sky News, also include information on satellite communication devices used by the global shipping industry as well as a computer-based system that controls things like lights, heating and ventilation in smart buildings across the world.

Sky's foreign affairs editor Deborah Haynes reports.

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