Investigators have released a report on missing Malaysia Airlines flight MH370 saying the plane's controls were likely deliberately manipulated to take it off course, but they were not able to determine who was responsible.

Head investigator Kok Soo Chon said, while its unlikely a deliberate diversion by the pilot or first officer, they cannot exclude the possibility of a third party interference.

In their report, the investigators had no conclusion about what happened aboard the plane that vanished with 239 people en route to Beijing from Kuala Lumpur on March 8, 2014, leaving one of the world's greatest aviation mysteries unsolved.

On 29 May, Malaysia called off a three-month search by US firm Ocean Infinity spanning 112,000 sq km in the southern Indian Ocean that ended with no significant findings.

It was the second major search after Australia, China and Malaysia ended a fruitless search across an area of 120,000 sq km (46,332 sq miles) last year.

Malaysian and international investigators have been looking into why the Boeing 777 jet veered thousands of miles off course from its scheduled route before eventually plunging into the Indian Ocean.