Shipping containers from China and other Asian countries are unloaded at the Port of Los Angeles as the trade war continues between China and the US, in Long Beach, California on September 14, 2019. -

The tariff waivers will apply to four chemical products, such as metallocene high-density polyethylene (HDPE) and a special grade of linear low-density polyethylene (LLDPE), and refined oil products that include white oil and food-grade petroleum wax.

Duties already imposed on U.S. products would not be refunded, the ministry added.

The exemptions will be for one year from Dec. 26, the Finance Ministry said, without providing a value for the imports excluded from duties.

China on Thursday unveiled a new list of import tariff exemptions for six chemical and oil products from the United States, days after the world's two largest economies announced a phase one trade deal.

Kelly Cui, principal analyst with consultancy Wood Mackenzie, said the exemptions on the chemical products would benefit companies such as Dow Chemical, Exxon Mobil, and Chevron Phillips Chemical, which have since 2017 been adding shale-based ethylene production facilities and targeting China as the prime export market.

Cui also pointed out that the listed products, metallocene HDPE and LLDPE, were high-end special grade plastic raw materials used for packaging and pipes. China is the world's largest importer of polyethylene.

"The exemptions could see China resume buying more HDPE and LLDPE from the U.S., reversing the trade flow, as the U.S. supplies have been diverted to Latin America and Europe while China has been importing mostly from the Middle East," said Cui.

In 2018, China imported some 6.86 million tonnes of HDPE and 4.46 million tonnes of LLDPE, according to Cui, who cited Chinese customs data. The data does not provide a breakdown for different grades of each polymer.

These imports had a combined total value of about $14 billion, according to Reuters calculations based on the delivered cost for these two products.

For petroleum wax, China imported from the U.S. 1,108 tonnes or worth only $3.2 million in the first 10 months of 2019, one-tenth of China's total imports of the product, according to Chinese customs data and consultancy JLC Network Technology.

White oil imports from the U.S. were 3,490 metric tons or worth only $8.7 million during the same period, roughly 6% of China's total imports.

China waived import tariffs for some soybeans and pork shipments from the United States on Dec. 6, before the two sides reached a Phase 1 trade deal to cancel tariffs that were planned to take effect on Dec. 15.