Japan announced on Thursday that it will step up its activity in the disputed South China Sea through joint training patrols with the United States and bilateral and multilateral exercises with regional navies.

Japanese Defence Minister Tomomi Inada said in a speech at the Centre for Strategic and International Studies that Japan has increased its engagement in the area and it would include capacity building for coastal nations.

Apart from South China Sea, Japan also has its own conflict with China over territories in the East China Sea.

Inada added that the "consequences could become global" if the world excused attempts to change the rule of law and allowed "rule bending" to succeed.

"In this context, I strongly support the US Navy's freedom-of-navigation operations, which go a long way to upholding the rules-based international maritime order," she told Reuters.

Inada also added: "Japan, for its part, will increase its engagement in the South China Sea through, for example, Maritime Self-Defence Force joint training cruises with the US Navy and bilateral and multilateral exercises with regional navies."

Before heading for talks with US Defence Secretary Ash Carter at the Pentagon, Inada said Japan would surely help to build the capacity of coastal states in the South China Sea

Earlier this month, Japan said it was ready to provide new patrol ships to Vietnam. Experts see this move as the latest step to boost the maritime law-enforcement capabilities of countries which are locked in territorial rows with China.

Japan also promised the Philippines to provide two large patrol ships and lend up to five used surveillance aircraft.

"The United States welcomes Japan's interest in expanding its maritime activities in the South China Sea. We continue to explore ways to enhance US-Japan cooperative efforts to contribute to the security and stability of the region," the US Navy said in response to Inada's comments.