MANILA (AFP) - A Filipino paratrooper has died while taking part in joint United States-Philippine military exercises, the two allies said on Friday (April 8).

The air force soldier plunged into the sea at Subic Bay, about 85km north-west of Manila during a parachute jump exercise on Thursday, they said.

"(The) soldier from the Philippine side... accidentally dropped into the sea nearby Subic airport due to wind drag," a Philippine military statement said after the paratrooper was blown off course by a strong gust of wind.

The paratrooper was pronounced dead at a hospital shortly after rescuers plucked him from the water, it added.

The two sides said they are investigating the incident.

The 11-day manoeuvres involving 5,000 US troops and nearly 4,000 Filipino soldiers began at various locations in the Philippines on Monday.

"The safety of all the participants is a priority - always (has) been and always will be," Captain Alex Lim, US spokesman for the joint exercises, told AFP.

Capt Lim said he did not know if there had been previous deaths at the annual exercises.

This year's manoeuvres are widely seen as a show of strength by the United States and its two military allies, the Philippines and Australia, in the face of China's increasing assertiveness in the region.

US Defence Secretary Ash Carter is to fly to the Philippines next week to observe live-firing of artillery and visit US Navy ships taking part, American officials have said.

A total of 80 Australian military personnel are also involved.