Perth, May 13 (IANS): A shipwreck has been discovered off Western Australian coast during the search for the missing Malaysia Airlines flight MH370, a media report said on Wednesday.

Flight MH370 disappeared without a trace in March last year while on a flight from Kuala Lumpur to Beijing with 239 people on board, but is believed to have crashed in the Indian Ocean off Australia's west coast.

Australia's Joint Agency Co-ordination Centre (JACC) said on Wednesday that search vessel Fugro Equator's deep tow system picked up a cluster of small sonar detections in the southern part of the search area, which had "potential interest but (was) unlikely to be related to MH370", WA Today online reported.

A high-resolution sonar scan revealed many contacts at a depth of almost four km.

Most were the size of a cricket ball but some larger items were also found, the biggest of which was box-shaped and about six metres long.

Poor weather hampered operations for several days before images of the field were obtained and analysed this week, indicating the debris was a previously uncharted shipwreck.

JACC said the images would be provided to expert marine archaeologists for possible identification.

About 75 percent of the initial search area has been combed so far.

If the jetliner is not found in the remaining zone, the search will be extended to an area of 120,000 sq.km.