Beijing must offer more than hollow promises if it wishes to secure peace in the disputed South China Sea and beyond, a spokesman for the Philippine defence department said Sunday.

The remarks came days after China flaunted its military might with a massive parade to mark the end of World War II, though President Xi Jinping said at the event his country was dedicated to peace and does "not seek hegemony".

"The Chinese leadership should go beyond deceitful rhetoric claiming peaceful efforts before their aggression takes a greater and irreparable toll on the region and beyond," Peter Paul Galvez, the department spokesman said in a statement.

"We call on China's government to show its sincerity by, at the least, stopping all ongoing construction and militarisation activities and to refrain from restricting freedom of flight and navigation," in the flashpoint sea, he said.

China claims almost all of the South China Sea -- a vital maritime route, rich fishing ground and potential source of vast minerals -- despite competing claims from the Philippines as well as Brunei, Malaysia, Taiwan and Vietnam.

The Philippines has been the most vocal in criticising China's efforts to enforce its claim by seizing islets and turning isolated outcroppings into artificial islands that can host military facilities.

Galvez added, "the department welcomes the Chinese leadership's recent pronouncement that they are committed to peace. But why the display of offensive weaponry (at the September 3 parade)?"

The Philippines, which has one of the weakest militaries in the region, has been seeking to improve its defence relations with other countries like the United States and Japan to counterbalance China's forces.

The country has also filed a case with an international tribunal challenging China's maritime claim.