China's government has passed new guidelines requiring civilian shipbuilders to ensure their vessels can be used by the military in the event of conflict, state-run media said on Thursday.

The regulations require five categories of vessels including container ships to be modified to "serve national defence needs", the state-run China Daily newspaper said.

The regulations "will enable China to convert the considerable potential of its civilian fleet into military strength", it said.

The report said that China had about 172,000 civilian ships at the end of last year, suggesting the measure could be a major boost to China's navy.

China's government will cover the costs of the plan, it added.

China has rapidly expanded its navy in recent years, commissioning its first aircraft carrier in 2012 and adding to its submarine and surface fleets.

The increased military spending comes as Beijing asserts its territorial claims in the East and South China Seas, where it has disputes with several Asian neighbours.

"Naval warfare often requires the mobilisation and deployment of a large number of ships," the China Daily quoted army researcher Cao Weidong as saying.

"It is a common practice that shipbuilders reserve some military application platforms on their civilian vessels so they can serve the navy in wartime," he said.

"The new standards will help translate the private shipbuilding sector's strength into military prowess."

China said last month it will project its military power further beyond its borders at sea and more assertively in the air, defending the construction of artificial islands in the South China Sea which sparked concerns in Washington.