China should have at least three aircraft carriers to defend its national interests at sea, a mainland naval expert said, adding that criticism overseas of an expansion of the fleet was an overreaction.
Three carriers would just meet the most basic demands of China's navy, said Li Jie, a researcher at the Naval Military Studies Research Institute.
"Among three carrier fighting groups, just one would able to carry out operational missions because one would be used for training, while the third would have to undergo maintenance," he said.
China now has one aircraft carrier, but the Communist Party chief in Liaoning province Wang Min said earlier this month that a second was being built in Dalian . Reports of his comments were later deleted from the internet.
Li dismissed reports overseas that the PLA would be able to deploy three carriers by 2020, one in the East China Sea and two in the South China Sea.
"It's impossible for China to complete the construction of three carrier fighting groups by 2020 based on current shipbuilding capabilities and other technical reasons," he said.
Li said China had two yards capable of building aircraft carriers, at Dalian Shipbuilding Industry and the Shanghai-based Jiangnan Shipyard.
"Besides the Dalian dockyard which successfully refitted the Soviet-built Liaoning carrier for China, the Shanghai shipyard is also in a position to build an aircraft carrier, too."
He declined to comment on whether the Dalian yard was building a second carrier.
Li wrote an article in the state-controlled Global Times this week criticising the United States and India for voicing disquiet about China's aircraft carrier programme.
"The United States always wants to be the world's largest power. It always overreacts to China's military development," he wrote.
"Anything China has done, no matter if it is a new generation of stealth fighter or just a refixed training carrier, seems to make Uncle Sam nervous."
Li said Beijing should be more open about the need for more carriers to ease disquiet among its neighbours and superpowers like the US.
He said aircraft carriers would continue to be an essential tool in China's defence and that other nations including the US and India were continuing to develop their fleets.
"The carrier will still have naval supremacy in this and the next century and will be the best weapon in great power's navies," he wrote.
Meanwhile, two missile destroyers have set off for naval exercises in the South China Sea, the Pacific and the Indian Ocean, the navy's website reported.