MH370 search crews find shipwreck in the Indian Ocean off the western coast of Australia

The previously uncharted shipwreck was discovered after sonar equipment detected a cluster of objects 2.5 miles below the surface of the water

A previously uncharted shipwreck discovered in the southern Indian Ocean during the search for flight MH370 (AFP/Getty Images)

The search for missing Malaysia Airlines flight MH370 has discovered a previously uncharted shipwreck in the Indian Ocean off western Australia, officials have said.

The discovery occurred after a cluster of objects almost 2.5 miles below the surface of the water was detected by sonar equipment on one of the vessels searching for the missing jetliner, the Australian Transport Safety Bureau has said.

Work is now underway to identify the ship, which is believed to have been built in the 19th century.

“It's a fascinating find, but it's not what we're looking for,” Peter Foley, ATSB's director of the operational search, said.

A previously uncharted shipwreck discovered in the southern Indian Ocean during the search for flight MH370 (AFP/Getty Images)

A previously uncharted shipwreck discovered in the southern Indian Ocean during the search for flight MH370 (AFP/Getty Images)

“We're not pausing in the search for MH370, in fact the vessels have already moved on to continue the mission.”

Following the discovery of the debris, authorities decided to take a closer look despite suspicions it did not belong to the Boeing 777, which has been missing since 8 March 2014.

An unmanned submarine was sent down to investigate the wreckage, which revealed a large number of small objects and several larger items.

Cambodian residents light candles as they pray for the missing Malaysia Airlines flight MH370 at their village in Phnom Penh on 17 March, 2014 (TANG CHHIN SOTHY/AFP/Getty Images)

Photographs of the debris have now been analysed, with experts concluding it belongs to a previously uncharted shipwreck.

The wreck is believed to belong to a cargo ship built in the mid-to-late 19th century, according to Michael McCarthy, a senior maritime archaeologist at the West Austrlian Maritime Museum.

Mr McCarthy has said it could be one of hundreds lost on voyages across the Indian Ocean.

He said: “We've got quite a lot of stories about ships that sank in the Indian Ocean mid-voyage and you would be struggling to tell which is which unless you had a complete catalogue of all the ones lost.”

Mr McCarthy said experts had predicted crews searching for MH370 would find the wreckage of other ships, but added it would be a difficult task to identify this ship.

He said those identifying the ship would need to get a closer look and know which ports it was travelling between.

He said: “Being a fairly common type of cargo ship from the 19th century with no obvious cargo remains there, I doubt that anyone would pay the enormous cost of going down to look at it.”

Officials last month announced the search area for MH370 was to be expanded in the Indian Ocean by a further 60,000 square kilometers if the plane was not found by the end of May.

Crews have now covered 75 per cent of the original search area, it has been reported.

Additional reporting by AP