The four sites are considered "suitable and mutually beneficial", the Presidential Communications Office said in a statement.

The longtime treaty allies agreed in February to expand cooperation in "strategic areas" of the country as they seek to counter China's growing assertiveness over Taiwan and its building of bases in the South China Sea.

The 2014 Enhanced Defense Cooperation Agreement, known as EDCA, gave US forces access to five bases in the Philippines.

It was expanded to nine, but the locations of the four additional bases were withheld while the government consulted with local officials.

President Ferdinand Marcos has approved the use of three sites in the northern Philippines, including a naval base and airport in Cagayan province and an army camp in the neighbouring province of Isabela, the statement said.

The naval base at Cagayan province's Santa Ana is about 400 kilometres (250 miles) from Taiwan.

Another site will be on Balabac Island, off the southern tip of Palawan Island, near the South China Sea.