China's first aircraft carrier has entered into service, the Defence Ministry says. The 300m (990ft) Liaoning - named after the province where it was refitted - is a refurbished Soviet ship purchased from Ukraine. For now the carrier has no operational aircraft and will be used for training. But China says the vessel, which has undergone extensive sea trials, will increase its capacity to defend state interests. The delivery of the aircraft comes at a time when Japan and other countries in the region have expressed concern at China's growing naval strength. China and Japan are embroiled in a row over disputed islands in the East China Sea. Several South East Asian nations are also at odds with China over overlapping territorial claims in the South China Sea. 'Defend interests' The Liaoning was formally handed over to the navy at ceremony attended by top Chinese leaders at Dalian Port, state-run Xinhua news agency said. "Having the aircraft carrier enter the ranks will be of important significance in raising the overall fighting capacity of our nation's navy to a modern level," China's Defence Ministry said in a statement. The vessel will "increase [China's] capacity to defend, develop its capacity to co-operate on the high seas in dealing with non-traditional security threats and will be effective in defending the interests of state sovereignty, security and development", it added. The official commissioning of the country's first aircraft carrier signals China's status as a rising power, says the BBC's Damian Grammaticas in Beijing. The country's Communist leaders are spending billions modernising their armed forces so they can project military power far beyond China's borders, our correspondent adds. The Liaoning, formerly known as the Varyag, was constructed in the 1980s for the Soviet navy but was never completed. When the Soviet Union collapsed in 1991, the Varyag sat in Ukraine's dockyards. A Chinese company with links to China's People's Liberation Army (PLA) bought the ship just as Soviet warships were being cut for scrap. It said it wanted to turn the Varyag into a floating casino in Macau and in 2001 the ship was towed to China. The Chinese military confirmed in June 2011 that it was being refitted to serve as the nation's first aircraft carrier.