"Our country has an 18,000-kilometre (11,000-mile) long coastline. Also, our economy is outward looking and our interests abroad are growing," said Commodore Zhang Junshe, a member of the Naval Research Institute.

"All this requires us to send a military force to distant seas to protect (these interests). In these circumstances, I think we need at least three aircraft carriers. Of course, depending on economic development, we could legitimately revise this figure upwards," he said during a meeting with the Chinese and foreign press.

In November, the English-language China Daily, citing the official Xinhua news agency, said the Asian giant had begun construction of a third aircraft carrier. The defence ministry has not confirmed this.

China currently has only one operational aircraft carrier, the Liaoning, a secondhand Soviet ship built nearly 30 years ago and commissioned in 2012.

A second carrier -- the first built entirely by China and known only as "Type 001A" -- was launched a year ago and has been undergoing sea trials.

With just one fully operational aircraft carrier, China is far behind the United States, which has 11 such warships, but is on a par with Russia, France, India and Britain, which have one each, according to Nick Childs, a naval specialist at Britain's International Institute for Strategic Studies.

"Since the first Opium War in 1840 until the founding of the People's Republic of China in 1949, we have suffered 470 naval attacks from Western countries or Japan," said Zhang.

During this period, China suffered several defeats by Britain, Japan and France which resulted in the colonisation of Chinese territories.

"We will not be invading other countries, but the Chinese are afraid that their country will be invaded again, so the main reason we are strengthening our defence is to ensure our security," he said.

With a buildup of its military capability in recent years, Beijing is seeking to assert its extensive claims to the South China Sea and to deter any independence moves by Taiwan.