China has completed the major steps required to fully restore a partially built aircraft carrier purchased from Ukraine in 1998, the Hong Kong-based Kanwa Asian Defense magazine said in a report Wednesday.

The aircraft carrier, Varyag, is being worked on at a shipyard in Dalian, Liao-ning Province. All the living and work compartments, engines, navigation systems and power-generating equipment were restored, the report said.

Military sources said that many foreign media reports about China's plan to build an aircraft carrier are based on satellite images, and those reports may not be completely wrong.

Li Jie, a researcher at the Naval Research Institute in the PLA navy, told the Global Times that the visible parts of the aircraft carrier, such as the radar system and the communication equipment, could be seen by a satellite.

"The construction of an aircraft carrier always follows a certain procedure, so the completion time could be deduced from the visible parts on the deck," Li added.

"In 2009, China put forward a plan and a program for building an aircraft carrier," according to China's Ocean Development Report (2010), a book published in May by the State Oceanic Administration, which is under the Ministry of Land and Resources.

"This shows that China has started entering a new historic era of comprehensively building itself into a great naval power," the report said.

China apparently purchased Russian SU-33 carrier-based fighters and has modified domestic J-11 jets for carrier landings and takeoffs, according to the Associated Press.

Reuters reported last month, citing an anonymous source, that China could put the carrier into use around July 1 this year, when it plans to celebrate the CPC's 90th birthday. It would be one year ahead of US analysts' expectations.

He Jun, a senior researcher at the Anbound Information Group, wrote in an article that the construction and maintenance of aircraft carriers would challenge the country financially.

It costs $2.02 billion for the US to build a conventionally powered aircraft carrier, and more than $10.4 billion for the maintenance work including the cost of personnel staff, fuel, repairs, and so on, according to He.

"The maintenance and usage of aircraft carriers cost 5.5 times more than the construction cost," He said.

Li Jie emphasized that aircraft carriers have strategic significance for a growing power such as China.

"Just like what Defense Minister Liang Guanglie said, the fact that China does not have its own aircraft carriers won't last forever," Li said, adding that China needs aircraft carriers to carry out marine missions and develop marine interests.