The finding eases blame on ship owners who were accused of being part of a sabotage plot after a dragging anchor left Tonga with drastically limited internet and phone services for 12 days.
The incident on 24 January sparked widespread panic and cost Tonga an estimated $US200,000.
Police launched an investigation in February to assess whether the damage to the cable was deliberate or accidental. A report was due back in July but police have refused to release the document or comment on the investigation.