Preliminary evidence indicates that imported pecans from those countries are being sold in China at prices below their normal value, Beijing's commerce ministry said in a statement on Thursday evening.

"This has reduced and suppressed the prices of similar products in the Chinese domestic industry, causing substantial damage" to it, the statement added.

It said the probe began on Thursday and was expected to conclude by September 25 next year.

China is the second-largest destination for Mexican pecans after the United States, accounting for around 14 percent of exports, according to data published in 2021 by the Mexican government.

The United States is the world's biggest producer of pecans, and exports to China were worth $93.1 million in 2023, according to the US Foreign Agricultural Service.

Beijing also said on Thursday that it had opened a probe into "restrictive measures" being considered by the Mexican government, which in September floated hiking its tariffs on car imports from China from around 15-20 percent to 50 percent.

The proposal came after pressure from the Trump administration, which has accused its southern neighbour of serving as a back door for bringing Chinese goods into the United States.

"These measures would seriously damage the trade and investment interests of Chinese companies," Beijing's commerce ministry said.

"Against the backdrop of the current United States' abuse of tariffs, all countries should jointly oppose all forms of unilateralism and protectionism, and must not sacrifice the interests of third parties due to coercion," a commerce ministry spokesperson said in a separate statement.

Mexico's President Claudia Sheinbaum has denied that the proposed new tariffs aim to coerce China.