Philippine and U.S. forces will simulate retaking enemy-occupied islands during joint military drills starting next week in areas facing Taiwan and the South China Sea as Manila shifts its focus to external defence.

The annual "Balikatan" or "shoulder-to-shoulder" drills, which will run from April 22 to May 10, will involve 16,700 soldiers who will train in maritime security, air and missile defence, dynamic missile strikes, cyber defence, and information operations.

It will be the first time the maritime exercises are carried out beyond Philippine territorial waters," said Michael Logico, a Philippine army colonel overseeing the exercises.

Aimed at improving interoperability between the two militaries, the drills come against the backdrop of China's recent aggressive behaviour in the South China Sea and the Taiwan Strait, flashpoints for Chinese and U.S. tensions.

Logico said U.S. troops and their Manila counterparts will simulate retaking islands occupied by hostile forces in the northernmost islands of the country, close to Taiwan and in the western Palawan province facing the South China Sea.

A small French contingent will join this year's drills for the first time since the annual exercise began in 1991, deploying a frigate that will sail jointly with Philippines and US naval vessels in Manila's exclusive economic zone in the South China Sea.

Around 14 nations will join as observers, including Japan, India and countries in ASEAN and the European Union, Logico said.

Like last year, next week's exercise will attempt to sink a mock enemy warship in the northern city of Laoag in Ilocos province.

(Reporting by Mikhail Flores; Editing by Michael Perry)