China's refitted aircraft carrier is seen in this undated file photo. [Photo/Xinhua]

DALIAN - China's refitted aircraft carrier left its shipyard at Dalian Port in northeast Liaoning province on Wednesday morning to start its first sea trial.

Military sources said that the first sea trial was in line with schedual of the carrier's refitting project and would not take a long time. After returning from the sea trial, the aircraft carrier will continue refit and test work.

The carrier was originally built by the former Soviet Union which named it Varyag yet failed to complete the ship's construction before collapsing in 1991. The still-unnamed aircraft carrier was an empty shell. Ukraine disarmed it and removed its engines before selling it to China.

China's Defense Ministry spokesman Geng Yansheng said on July 27 that the country is refitting an imported aircraft carrier for the purposes of scientific research and training.

The project embodies the capability of China's defense technology and will promote the modernization of the People's Liberation Army (PLA), Geng said.

The spokesman did not give further details about the carrier. However, Chinese military experts have provided a more detailed picture of the ship and its capabilities.

The carrier has a displacement of nearly 60,000 metric tons, putting it in the same class as Russia's commissioned carrier, the Admiral Kuznetsov, said Cao Weidong, a researcher with the PLA Navy's Academic Research Institute.

It is a conventionally-powered medium-sized carrier that will be equipped with indigenous Chinese engines, ship-borne aircraft, radar and other hardware, Cao said.

Fixed-wing aircraft on the carrier will use a ski-jump to take off from the vessel, instead of a catapult system, after the refitting is completed, Cao said.

Although the PLA has started training jet pilots with naval expertise since 1980s and begun to enrol trainees for ship-borne aircraft pilots in 2008, Cao said it will take the carrier's crew years to master takeoff and landing techniques in real maritime environments.