Philippine Foreign Secretary Alan Peter Cayetano is in Beijing for talks on joint development projects in the disputed South China Sea.

Cayetano is set to meet with his counterpart Wang Yi on Wednesday, a day after Chinese President Xi Jinping said China would never cede "one inch" of its territory in a fervently nationalistic address to the ceremonial legislature.

China rejected an international tribunal's 2016 ruling invalidating much of its claim to virtually the entire South China Sea in a case brought by the Philippines.

Since then, Philippine President Rodrigo Duterto has pushed for closer relations with Beijing, downplaying the dispute over territory claimed by both sides and courting Chinese aid and investment.

The South China Sea is believed to hold rich deposits of oil, gas and other resources.