Internet blackout

It's still unclear what caused the cut, which plunged Tonga into a 12-day internet blackout and also hampered international phone calls.

Police Commissioner Stephen Caldwell told Matangi Tonga the investigation would assess whether the damage to the cable was deliberate or accidental.

The Police Minister, Māteni Tapueluelu, said last week there appeared to be a "human factor" behind the damage.

The cable's owner, government-owned Tonga Cable Ltd, completed its initial investigation last week.

The Marshall Islands experienced a virtual internet blackout during that time, with access rationed for businesses.

That was alleviated when telecommunications authorities shifted communications to satellites and bought extra bandwith last week.

But RNZI's Marshall Islands correspondent Giff Johnson said the cable was turned back on last night following the completion of repairs and testing.