An undated file photo shows China's first aircraft carrier Liaoning. [Photo for chinadaily.com.cn]

China's second aircraft carrier, which is now under construction, will focus on military operations rather than training and technological experiments, according to a senior military researcher.

"This carrier will have different missions than those for the Liaoning (the country's first aircraft carrier)," Senior Captain Zhang Junshe with the People's Liberation Army Naval Military Studies Research Institute told the official PLA Daily on Friday.

"We use the Liaoning to test the reliability and compatibility of systems on carriers, and to train personnel. The second carrier will mainly do what a genuine aircraft carrier is supposed to do: running combat patrols and delivering humanitarian aid."

Zhang said China urgently needs a second carrier, as the country is seeking to improve its defense systems and better safeguard national interests.

"The PLA needs at least three aircraft carriers. When it does, one can be on duty, one can train personnel, and the third can receive maintenance," he said.

China's second aircraft carrier is under construction in the coastal city of Dalian, Liaoning province, Defense Ministry spokesman Yang Yujun told a news conference in Beijing on Thursday.

The Liaoning was originally a Soviet-era vessel and received an extensive refit at a shipyard in Dalian before going into service in September 2012.