The Philippines is buying nearly 100 new patrol boats to protect its fisheries, an official said Monday, in a substantial expansion from its current fleet of 20 as it responds to poaching by Chinese and Taiwanese vessels.

Most of the ordered vessels -- 71 short-range boats for coastal patrols and 27 able to go further out to sea -- will be delivered this year, Bureau of Fisheries and Aquatic Resources chief Asis Perez said.

"This is just fulfilling our mandate. Our country has eight times more sea area than land area. We have 36,000 kilometres (22,370 miles) of coastline and over 7,100 islands," he told AFP.

Perez said the "law-enforcement" boats would augment the agency's 20 patrol boats which protect the fisheries resources of one of the world's largest archipelagoes.

"We need additional vessels. These (new boats) are actually short of our needs but this is all we can afford," he added.

Perez said his agency is also seeking funding to acquire 10 larger boats that can patrol the high seas.

Numerous Chinese fishermen have been arrested by Philippine authorities for allegedly poaching in disputed waters.

Similar incidents involving Taiwan have also occurred, the latest in May off the northern Batan islands when the Philippine coast guard attempted to arrest a Taiwan fishing boat only to be blocked by the Taiwan coast guard.

The Philippines has recently been seeking to boost its poorly equipped military by acquiring new weapons, and deepening defence ties with allies like the United States and Japan.

The moves come after a series of confrontations at sea between the Philippines and both China and Taiwan.

Tensions have been rising in recent years due to China's more muscular approach to enforcing its claim to most of the South China Sea, even up to the coasts of its neighbours including the Philippines.

Chinese ships have occupied a reef near the western Philippines since 2012 following a tense stand-off with Philippine ships.

Confrontations between Philippine and Taiwan coast guard ships in their common maritime border have also risen recently following the 2013 fatal shooting of a Taiwanese fisherman by Filipino patrols there.