Taiwan President Tsai Ing-wen called on Tuesday for an alliance of democracies to defend against "aggressive actions" and protect freedom, alluding to Chinese actions in the South China Sea and Taiwan Strait as major threats to regional stability.

China, which claims democratic Taiwan as its own, has ramped up its military activities around the island, as well as in the disputed East and South China Seas.

Speaking in Taipei at a forum attended by top Taiwanese security officials and senior Western diplomats, Tsai said Taiwan stood at the forefront of defending democracy from "authoritarian aggression."

While Taiwan is committed to boosting its defensive capabilities, maintaining regional peace and security needs collaborative efforts, she added.

"The rapid militarization of the South China Sea, increasing and frequent grey-zone tactics in the Taiwan Strait and East China Sea, coercive diplomacy used against countries and corporations ... are all destabilizing the Indo-Pacific region," Tsai said, without directly naming China.

"It is time for like-minded countries, and democratic friends in the Indo-Pacific region and beyond, to discuss a framework to generate sustained and concerted efforts to maintain a strategic order that deters unilateral aggressive actions."

She called for a strategy that avoided war, yet conveyed the resolve to protect democracies by encouraging cooperation, transparency and problem-solving through dialogue.

China has stepped up pressure on Taiwan to accept its sovereignty over the island, which has responded by seeking closer ties with what it calls "like-minded" democracies.

This is primarily the United States, but also includes Australia, the U.K., Canada, the European Union and Japan, none of which maintain formal diplomatic ties with Taiwan.

Apart from the United States, Taiwan's main arms supplier, the other nations generally only offer occasional moral support, such as calling for the World Health Organization to grant proper access to nonmember Taiwan.