The status of the disputed Minerva Reef is likely to come under scrutiny after a landmark ruling on China's activities in the South China Sea.

Photo: Supplied

The reef which lies between Tonga and Fiji is claimed by both countries and has been the cause of tension after Tonga's navigational beacons were destroyed by the Fijians about five years ago.

An International Law of the Sea specialist Donald Rothwell said that in the South China Sea decision, the Permanent Court of Arbitration laid down the characteristics for deciding the status of various land formations.

He said it meant the inherent worth of the Minerva Reef was now quite different.

"It may well seek to dampen some of the aspirations of the claimants because the reef might now be properly characterised as nothing more than being entitled to a 12 nautical mile territorial sea as opposed to a very expansive maritime claim to an exclusive economic zone and continental shelf."

But Professor Rothwell, who is head of the Australian National University's College of Law, said it was most unlikely the ruling would unravel arrangements on maritime boundaries in the region which have already been settled.

He said the ruling could also have a knock-on effect on Pacific island countries' control of their huge fishing resource.

Professor Rothwell said some states' 200 nautical mile Exclusive Economic Zones could be reduced as a result.

"We may well see not only a redrawing of the maritime entitlements in the South China Sea but also in some of these closely contested areas in the Pacific where we have a mix of islands whose status is not really in doubt, but very small maritime features which are very remote, but which some South Pacific states may well have been seeking to rely upon to extend their maritime entitlements even further into the Pacific," he said.

Professor Rothwell said questions may also be raised over United States' seas extending out from Johnston Atoll in the Pacific which was built up for military purposes.