Mystery surrounds the fate of a Rio Tinto ship worker who boarded a iron ore freighter destined for the Pilbara and vanished in international water

Hope is slowly fading for a Rio Tinto deck fitter who disappeared on a bulk carrier bound for Western Australia from China.

Rio Tinto confirmed on Thursday that Philippine national Gel Aguaviva, 44, went missing on the RTM Zheng He in international waters en route to the Pilbara at about 9am on December 26.

An ‘extensive’ and ongoing search and rescue operation has been underway since then.

The ship’s crew is cooperating with international authorities and the Philippine Coast Guard, which are leading the operation.

“Our thoughts are with Gel’s family, friends and colleagues, and we stand with everyone affected by this distressing situation,” Rio Tinto CEO Jakob Stausholm said.

‘We are focused on providing all possible support during this difficult time.

‘We would like to thank everyone involved in the search for their tireless efforts.’

Authorities now believe Mr Aguaviva went overboard from the port side of the Singaporean flagship.

An extensive search and rescue mission is underway in the Sulu Sea in an attempt to find Mr Aguaviva

The ship was in international waters in the Sulu Sea, west of the Philippines, when Mr Aguaviva first went missing.

The Philippine Coast Guard said Gel Aguaviva was last seen on the ship’s main deck on the port side, wearing a blue reflective suit.

He was reportedly heading to the boatswain’s shop, which typically contained materials used by the ship’s sailors at the time.

Crew members did not realize Mr. Aguaviva had disappeared until just after 11 a.m ABC reported.

The ship will arrive at Dampier Port in WA on Saturday.

According to marinetraffic.com, it is currently crossing the Timor Sea.

The carrier is almost 300 meters long and 50 meters wide.

Bulk carrier RTM Zheng He is currently en route to the Pilbara after departing from China