A piece of suspected plane wreckage found off the east coast of southern Thailand on Saturday was unlikely to belong to Malaysia Airlines Flight MH370 which vanished nearly two years ago, said aviation experts.

A large piece of curved metal washed ashore in Nakhon Si Thammarat province, Tanyapat Patthikongpan, head of Pak Phanang district, told Reuters. Villagers reported it to authorities for identification, he said.

"Villagers found the wreckage, measuring about 2 metres wide and 3 metres long (6.6 by 9.8 feet)," he said.

The find fuelled speculation in the Thai media that the debris could belong to MH370, which disappeared with 239 people on board during a flight from Kuala Lumpur to Beijing in March 2014.  A piece of the plane washed up on the French island of Reunion in July 2015 but no further trace has been found.

Experts said that while powerful currents sweeping the Indian Ocean could deposit debris thousands of kilometres away, wreckage was extremely unlikely to have drifted across the equator into the northern hemisphere.

The location of the debris in Thailand "would appear to be inconsistent with the drift models that appeared when MH370's flaperon was discovered in Reunion last July," said Greg Waldron, Asia Managing Editor at Flightglobal, an industry publication.

"The markings, engineering, and tooling apparent in this debris strongly suggest that it is aerospace related," said Waldron. "It will need to be carefully examined, however, to determine it's exact origin."

Other possible sources of aerospace debris included the launching of space rockets by India eastwards over the Bay of Bengal, he said.

There has been no official confirmation from Thailand that the wreckage belongs to a plane. And Patthikongpan added that "fishermen said it could have been under the sea for no more than a year, judging from barnacles on it."

A spokesman for the Joint Agency Coordination Centre, the Canberra-based authority which is overseeing the international search for MH370, told Reuters it was "awaiting results of the official examination of the material."

The Malaysian transport ministry is in contact with Thai authorities to verify the debris, a ministry spokesman said.

Investigators believe someone may have deliberately switched off MH370's transponder before diverting it thousands of miles off course. Most of the passengers were Chinese.

Lingering uncertainty surrounding its fate has tormented the families of those on board. Some have said even the discovery of debris would still not solve the mystery.