Defense Ministry spokesman Geng Yansheng’s comments appeared to indicate China has no plans to deploy the restored carrier as part of a battlegroup, but will use it instead as a blueprint for indigenous flattops.

The remarks were a step toward clarifying China’s carrier ambitions that have sparked concern among neighbors amid heightened tensions over territorial disputes around Taiwan and in the South China Sea.

Geng told reporters that work was under way on refitting an old carrier, a reference to the Varyag, whose stripped-down hull was towed from Ukraine in 1998 and has been under reconstruction for the best part of a decade.

"Building an aircraft carrier is extremely complex and at present we are using a scrapped aircraft carrier platform to carry out refurbishment for the purposes of technological research, experiments and training," Geng said at a month-end news conference.

Although widely known for years, China has only recently acknowledged work was proceeding at the northern port of Dalian. Chief of Staff Chen Bingde was quoted by a Hong Kong newspaper in June as saying the carrier was being outfitted, but did not give a timetable for its completion.

Other reports say sea trials for the carrier could begin as early as this summer, which could aggravate neighbors amid recent run-ins with Chinese vessels in disputed, potentially oil- and gas-rich waters of the South China Sea.

Defense experts say up to four carriers are planned in all, with preparations under way at a Shanghai shipyard.

"They are indirectly telling us that China will be building its own carriers," said Andrei Chang, a leading expert on the People’s Liberation Army and editor of Kanwa Asian Defense magazine.

Work on China’s own flattops would begin "very, very soon," Chang said, adding they would likely be near copies of the Varyag. Chang said he learned during a recent trip to Eastern Europe that a large number of Ukrainian naval engineers were preparing to leave for China in September, apparently to help with carrier building.

At the same time, Chang said China has been working on a carrier-based fighter derived from the Russian Su-33, dubbed the J-15, and is planning to use its JL-9 jet trainer to bring pilots up to speed for carrier landings and take offs.

Chang said the announcement had been carefully planned in advance in an attempt to clear the air amid swelling online discussion of the carrier and speculation over its future role.

Following the announcement, which was posted to the Defense Ministry’s website, state broadcaster CCTV ran more than an hour of prepared coverage showing footage of the carrier and interviews with defense experts echoing the official line that it was purely for defensive purposes.

Activity aboard the ship has picked up in recent weeks, with photos on military enthusiast websites showing workers removing heavy equipment from its sloped flight deck. However, crucial equipment such as high frequency antennae and arresting cables have yet to be installed and final stability tests must be conducted before it can head out to sea.

Yet to be officially renamed, the carrier was bought as an empty shell without engines, weapons systems, or other crucial equipment. The Chinese buyers at the time said they were buying it to use as a floating casino, only for it to turn up later in Dalian.

China’s moves toward deploying a carrier or carriers raises the stakes for Washington, long the pre-eminent naval power in Asia, and jangles the nerves of China’s neighbors upset over Beijing’s more assertive posture in enforcing claims to disputed territories.

Over the past year, China has seen a flare-up in territorial spats with Japan, the Philippines and Vietnam and seen its relations strained with South Korea — all of which have turned to Washington for support.

Chinese commentators have sought to allay those fears by pointing out that other Asian nations, including India and Thailand, already possess carriers and that China needs them to protect its vast coastline, trade routes and other oceanic interests.

"We will stick to our defensive policy and simply having this platform or any number of carriers won’t change that. Conflicts will still be resolved peacefully," Academy of Military Science researcher Du Wenlong said.