The Philippines said Friday it had opened a coast guard post in the country's far north to boost security following China's "military build-up" near Taiwan over the past two years.

The outpost "shall gather essential maritime data and intelligence, enabling the (Philippine Coast Guard) to respond effectively to threats such as illicit trade, trafficking, piracy, and foreign intrusions", National Security Adviser Eduardo Ano said in a statement.

"In 2022, the area around Itbayat witnessed a military build-up as China responded to political developments between Taiwan and the United States," Ano said, announcing the opening of the station on the Philippines' northernmost inhabited island.

Itbayat is located around 150 kilometres (93 miles) south of Taiwan's south coast.

"Securing peace, stability, and freedom of navigation along the Luzon Strait is crucial for ensuring Philippine national security and economic prosperity," Ano said.

Ano added that he sees the Luzon Strait, which lies between the Philippines and Taiwan, both as a "vital international waterway" and "a potential flashpoint for regional and international conflicts".

It was the focus earlier this month of major annual joint military exercises between Manila and its longtime ally the United States.

These included using missiles and artillery to repel an imaginary invasion force off the northwest of the Philippines' main island of Luzon.

Last year the Philippine government also granted the US military use of a navy base on Luzon's north coast and a nearby airport as part of a defence cooperation agreement.

Beijing and Manila are in a bitter diplomatic dispute over rival claims to parts of the South China Sea.

China has built artificial islands and military installations in waters close to the Philippines.

Its efforts to enforce its claims have in recent years included water cannon attacks by China Coast Guard vessels that damaged Philippine government boats and injured several crew members.

Itbayat is just outside the area designated by a vaguely defined map of dashes that China uses to claim most of the South China Sea.

Ano made no reference to war games that China began on Thursday in which it encircled Taiwan with warplanes and naval vessels.