Chinese dredging vessels, Mischief Reef
China has turned submerged reefs into artificial islands in the South China Sea through a massive dredging project US Navy/Reuters

The Chinese navy has conducted live-fire exercises in the disputed South China Sea from where an estimated $5tn (£3.3tn) of maritime trade passes each year. China's defence ministry said the drills were routine, even though other countries have made claims over various parts of the disputed territory.

"The People's Liberation Army Navy in recent days organised a fleet to go to relevant seas in the South China Sea, by way of the Western Pacific, to carry out exercises," China's Defence Ministry said in a statement. "This action is a routine arrangement made in accordance with this year's naval training plan."

Chinese state-run media on its Twitter feed posted images of the live-fire drill conducted by the Chinese navy. It wrote: "InPic: #Striking moments of the live fire #drill conducted by South #China Sea Fleet lately." The People's Daily, however, did not mention the exact location where the exercise was conducted.

The US has criticised China for constructing artificial islands in the South China Sea's disputed Spratly archipelago. According to reports, the US would position its P-8 Poseidon spy plane in Singapore to monitor the disputed location. The plane has the capability to carry torpedoes and cruise missiles. Last month, the US had flown its B-52 bombers near some of the artificial islands built by China, and in October this year, US warship USS Lassen came within 12 nautical miles of China's claimed waters increasing tension in the area.

The US Department of Defense in a statement said the US and Singapore have "agreed on a broad framework for defence cooperation in five key areas, namely in the military, policy, strategic and technology spheres, as well as cooperation against non-conventional security challenges, such as piracy and transnational terrorism".

The Philippines, Brunei, Vietnam, Malaysia and Taiwan have claimed various parts of the disputed territory with China holding a large portion. The region gains significance because of the maritime trade it brings and the resources that lay beneath the sea floor.