Malaysia said further examination was required to verify if the debris belonged to MH370.
An international team of investigators probing the loss of flight MH370 will issue a statement on Tuesday
The latest find comes just days before the disaster's two-year anniversary.
The debris will be tested by officials in Australia, with help from Malaysian authorities and representatives of manufacturer Boeing Co.
“There’s always this question: Have we missed something?”
The search area has been expanded to 120,000 square km (46,330 square miles) of ocean floor.
Serial numbers for the part assembly, wire bundle and bolts part don’t match those of a Boeing Co. 777
The towfish and 4,500 metres of cable are now resting on the sea floor
The debris "could have been under the sea for no more than a year, judging from barnacles on it."
The Malaysian transport ministry is in contact with Thai authorities to verify the debris, a ministry spokesman said.
Investigators are now focusing on the southern end of a refined 100,000-square-kilometer (39,000-square-mile) search...
A numbers found on the flaperon is identified as being the serial number of the MH370 Boeing 777.
"This kind of closed, unjust, and totally inefficient investigation is really hard ... to understand."
Most families have refused to accept the Malaysian verdict, and are awaiting a more definite and conclusive analysis