China's decision to impose tariffs on imports of soybeans from the United States is 'regrettable' and 'won't solve the trade imbalance', the China director of the U.S. Soybean Export Council said on Wednesday.

U.S. soybean futures fell more than 5 percent following the announcement. A Beijing-based soybean trader said there are growing concerns about the cancellation of previously purchased cargoes by the world's top buyer of the oilseed.

Soybeans, the top U.S. agricultural export to China, were among the 106 U.S. products on which Beijing plans to impose an additional 25 percent in tariffs.

The U.S. is the second-biggest soybean supplier, after Brazil, to China, the world's largest consumer of the bean.

The move had been expected by the U.S. soybean industry, China Director Zhang Xiaoping told Reuters, despite the Council, which represents American soybean producers, having done "everything" to prevent it.

China may still buy U.S. soybeans, despite the additional tariff, if the market needs supplies, added Zhang.

However, the Beijing-based trader said he had already received calls from customers who are worried about the tariffs being applied to cargoes not yet shipped.

"Some customers still have contracts in hand. They will wash out those cargoes (if the duties are implemented soon)," said the trader, who works for an international firm and declined to be identified.

The effective date for the tariffs was not announced, but China's Ministry of Finance said it was dependent on the $50 billion in tariffs due to be adopted by the administration of U.S. President Donald Trump.