BEIJING — Taiwan has protested its exclusion from a United Nations conference on the global fishing industry, allegedly at the behest of chief rival China, the official Central News Agency reported.

CNA said in a report late Wednesday that the Foreign Ministry delivered a letter to the Food and Agricultural Organization protesting against what it called “discriminatory treatment” against two Taiwanese representatives who were barred from the organization’s Committee on Fisheries meeting being held in Italy this week.

It said China, which claims sovereignty over Taiwan, was behind their rejection but did not say how that information was obtained.

Taiwanese representatives had participated in the biennial conference since 2003 as experts or members of non-governmental organizations.

As a major deep-sea fishing nation, Taiwan had argued that its presence at the conference was appropriate and necessary.

However, the exclusions are seen as the latest sign of how China is tightening the diplomatic screws on Taiwan as a way of pressuring the island’s new independence-leaning president, Tsai Ing-wen.

Taiwan is excluded from the United Nations at China’s insistence, but has been able to attend some technical conferences held under U.N. auspices as long as they’re not of a political or diplomatic nature.

China has also restricted numbers of Chinese tourists visiting Taiwan and cut off contact with the main Taiwan liaison body because of Tsai’s refusal to endorse the concept of a single Chinese nation. Many are watching for signs that it will begin picking off Taiwan’s handful of remaining diplomatic allies as a means of further isolating the island.