MANILA (AFP) - The Philippines is planning a 25 per cent hike in its defence budget next year, mainly to bolster its claims in the disputed South China Sea, officials said on Tuesday.

The proposed 2016 national budget, which President Benigno Aquino is to present to parliament for approval on Monday, would reserve a record 25 billion pesos (S$756,250) for defence spending.

Funds would be used to acquire navy frigates and patrol aircraft, budget and defence officials told AFP.

"We need to protect what is clearly within our territorial jurisdiction," Budget Secretary Florencio Abad said, when asked if the increase was due to the Philippines' maritime row with China.

"Certainly, we need to at least be able to effectively monitor the developments in the area, particularly those in disputed zones," he added.

Under the three-trillion-peso budget bill, defence spending would be up from a 20-billion-peso military budget last year and five times bigger than in 2013, the officials said.

The proposed 2016 defence budget is part of a five-year, 75-billion-peso military modernisation programme approved by Aquino in 2013, Abad said.

The amount would still be dwarfed by China, which claims most of the South China Sea including areas close to the shores of its Asian neighbours.

Beijing budgeted $142.9 billion for its military this year.

- Modernisation catch-up -

One of the region's most poorly equipped, the Philippine military relies on half-century old ships and aircraft keeping watch over the South China Sea, where tensions have flared recently.

The Philippines is catching up on military modernisation after spending was held back to just five billion pesos in 2013 as the government shifted resources to recovery from Super Typhoon Haiyan, which struck the country that year leaving 7,350 people dead or missing.

The Philippine military's mission to protect the country's territory is complicated by long-running communist and Muslim insurgencies that forces it to devote troops and equipment for internal security.

While China has gone on an island-building frenzy to reinforce its claims on South China Sea reefs and waters, the Philippines has set repairs on a crumbling World War II ship that serves as its lonely outpost there.

The BRP Sierra Madre, emblematic of the Philippine military, was deliberately grounded on Second Thomas Shoal in 1995 in a desperate move to check China's advance in the Spratly islands.

The South China Sea chain is also disputed in whole or in part by Brunei, Malaysia, Taiwan and Vietnam.

"This budget will allow us more latitude in acquiring new assets for the Armed Forces of the Philippines," defence department spokesman Arsenio Andolong said.

"We are pushing hard on modernisation and we will need all the help we can get.... This includes the purchase of frigates and patrol aircraft."

Two of 12 fighter jets that the Philippines had bought from South Korea are expected to be delivered as early as November, he said.

A United Nations-backed tribunal is expected to decide in months whether it has jurisdiction over a Philippine petition to declare China's claims as illegal.

Beijing has refused to cooperate in the arbitration proceedings.