There are signs that Vietnamese businesses are involved in exporting Chinese plywood to the U.S, the Ministry of Industry and Trade said, adding that the U.S. is investigating American importers suspected of buying plywood products from China.

Plywood is one of the Chinese products on which U.S. President Donald Trump has imposed a 25 percent tariff. 

Vietnam's plywood exports to the U.S. in the first quarter rose 95 percent year-on-year to $47 million, according to Vietnam Customs. Imports from China rose 37 percent in the same period to $61 million, accounting for 84 percent of all plywood imports.

Vietnam Customs has red flagged four local wood producers for the sudden surge in exports to the U.S. this year, suspecting them of having imported plywood products from China.

It has also suggested a regulation which requires Vietnamese producers to register their plywood export batches so that they can be traced.

Plywood exports to the U.S. last year surged 2.7 times from 2017 to $190 million, according to the Vietnam Timber and Forest Product Association.

Vietnam exported $650 million worth of plywood last year, up 76.5 percent from 2017, according to Vietnam Customs.