Over fears of trade barriers, tech giant Apple asked suppliers to ensure that shipments heading from Taiwan to China strictly comply with Chinese customs regulations following US House Speaker Nancy Pelosi's controversial visit to the island, Nikkei reported.

Sources familiar with the matter told Nikkei that Apple informed suppliers that Beijing has started strictly enforcing a rule that Taiwanese products must be labeled as being made in "Taiwan, China" or "Chinese Taipei".

According to the sources, Apple urged suppliers to deal with the matter with urgency to avoid possible shipment disruptions.

The sources explained that using "Made in Taiwan" could cause shipments to be held and checked by Chinese customs.

One of the sources even indicated that the penalty for violating the Chinese rule is a fine of up to 4,000 yuan ($592) or the shipment being rejected.

According to Nikkei, Apple's warning comes after shipments that headed from Taiwan to one of iPhone assembler Pegatron's facilities in China were held for review on Thursday to check if the import declaration form or cartons are labeled with "Taiwan" or "Republic of China."

The news agency pointed out that the Chinese measures came after Pelosi met with a senior Pegatron executive and other Taiwanese chip industry leaders at a lunch hosted by President Tsai Ing-wen.

"The timing is sensitive for Apple, as its suppliers are preparing components that will go into its next iPhones and other new products set to launch this autumn," Nikkei noted.

It is noteworthy that China considers Taiwan a part of its territory.

On August 3, China's Foreign Minister Wang Yi said the Chinese government will undoubtedly complete the process of reunification with Taiwan.

Commenting on Pelosi's visit to Taiwan, Wang affirmed that "Taiwan is a part of China. The implementation of national reunification is a general trend and historic imminence."

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