YOKOHAMA, JAPAN: Japan on Tuesday unveiled its biggest warship since World War II, a huge flat-top destroyer that has raised eyebrows in China and elsewhere because it bears a strong resemblance to a conventional aircraft carrier.

The ship, which has a flight deck that is nearly 250 metres (820 feet) long, is designed to carry up to 14 helicopters. Japanese officials say it will be used in national defence — particularly in anti-submarine warfare and border-area surveillance missions — and to bolster the nation's ability to transport personnel and supplies in response to large-scale natural disasters, like the devastating earthquake and tsunami in 2011.

Though the ship — dubbed "Izumo" — has been in the works since 2009, its unveiling comes as Japan and China are locked in a dispute over several small islands located between southern Japan and Taiwan. For months, ships from both countries have been conducting patrols around the isles, called the Senkaku in Japan and the Diaoyu in China.

The tensions over the islands, along with China's heavy spending on defence and military modernisation, have heightened calls in Japan for beefed-up naval and air forces. China recently began operating an aircraft carrier that it refurbished after purchasing from Russia, and is reportedly moving forward with the construction of another that is domestically built.