Chinese customs officers in eastern Shandong province have seized 60,000 maps that mislabelled the self-governed island of Taiwan, which Beijing claims as part of its territory.

The maps, authorities said, also omitted important islands in the South China Sea, where Beijing's claims overlap with those of its neighbours, including the Philippines and Vietnam.

The problematic maps, meant for export, cannot be sold because they endanger national unity, sovereignty, and territorial integrity of China, authorities stated.

Maps are a sensitive topic for China and its rivals for reefs, islands, and outcrops in the South China Sea.

China Customs indicated that the maps did not include the nine-dash line, which defines Beijing's claim over nearly the entire South China Sea. This line consists of nine dashes extending hundreds of miles south and east from Hainan province.

Moreover, the maps incorrectly marked the maritime boundary between China and Japan, and authorities noted that they mislabelled Taiwan without specifying the exact errors.

China considers self-ruled Taiwan as its territory and has not dismissed the use of force for reunification, while Taiwan views itself as a separate nation with its own constitution and democratically elected rulers.

Tensions in the South China Sea have recently heightened, highlighted by a maritime incident involving Chinese and Philippine vessels, with accusations flying from both sides regarding aggressive maneuvers.

While this seizure of maps is unusual in scale, China's customs frequently confiscate items that do not meet national standards. Previous incidents include the seizure of 143 nautical charts in March that featured significant inaccuracies regarding national borders.

With the Philippines and Vietnam being particularly sensitive to inaccurate map representations, the implications of China's customs actions resonate beyond its own borders, affecting regional security and diplomatic relations.