China surprised Taiwan with a move to block pineapple imports, stepping up economic pressure on President Tsai Ing-wen’s administration as it continues to spar with Beijing.

China will suspend imports of Taiwanese pineapples from March 1 after finding pests in recent shipments, China’s General Administration of Customs said in a statement on Friday. This move was a normal precaution to protect biosecurity and prevent the import of plant diseases, a spokesperson for China’s Taiwan Affairs Office said separately.

The move took Taiwan officials by surprise, Agriculture Minister Chen Chi-chung told reporters in Taipei on Friday. Beijing’s claims were “untrue” and 100% of exported pineapples had passed tougher inspections since last year, he said.

China has a history of using trade to help it achieve its policy goals. It imposed curbs on a string of Australian imports including coal, wine, beef and lobster as relations deteriorated after Canberra barred Huawei Technologies Co. from its 5G network and called for an independent probe into the origins of the coronavirus pandemic.

Pineapples are an important source of income for farmers in central and southern Taiwan. Around 11% of pineapples harvested in Taiwan are sold overseas, almost entirely to China.

While agriculture accounts for less than 2% of Taiwan’s $710 billion technology-dominated economy, farmers and related sectors remain an important constituency in Taiwanese politics, especially in the south.

China has increasingly stepped up pressure on Tsai, whose party supports independence. Chinese military jets have made almost daily incursions into Taiwan’s air defense identification zone in recent months.

China’s Communist Party asserts Taiwan is part of its territory, a claim Taiwan’s government rejects, viewing the islands as a de-facto independent nation.