Beijing on Tuesday launched a website for an uninhabited island chain in the East China Sea, in its latest bid to assert sovereignty over an archipelago controlled by Japan.

The new website, www.diaoyudao.org.cn, was unveiled by China's National Marine Data and Information Service.

It came as a trio of Chinese coastguard vessels made their latest patrol of the waters surrounding the archipelago, according to a notice posted on the website of the State Oceanic Administration.

Featuring a Chinese flag on its front page, the new website displays legal documents, maps and a timeline dating back to 1403, the year Beijing claims the islands' Mandarin name first appeared in writings.

The documents on the website "provide strong evidence, from both a historical and legal perspective, that the Diaoyu Islands are China's inherent territory since ancient times", the official Xinhua news agency wrote.

It added that the site, which is currently available only in Chinese, will soon be launched in at least seven other languages, including Japanese.

Beijing and Tokyo have been engaged in a bitter and longstanding battle over ownership of the island chain, known as Diaoyu in China and Senkaku in Japan.

The dispute was exacerbated when Japan nationalised some of the archipelago nearly two years ago, and the sea and air around the contested isles have seen increasingly dangerous standoffs since then.

Tokyo sought to further its claim to the territory in August by naming five of the islands, an act decried by Beijing as "illegal and invalid".

In November, a meeting between Chinese President Xi Jinping and Japanese Prime Minister Shinzo Abe raised hopes of a detente.

But two weeks later, Chinese ships returned to the territorial waters around the islands in their first patrol since the summit, with both sides warning the other to leave the area.

Japan's foreign ministry website already has a section on the islands, available in 12 languages.

"There is no doubt that the Senkaku Islands are clearly an inherent part of the territory of Japan, in light of historical facts and based upon international law," it says.

The disputed archipelago is not the only uninhabited territory to have a presence on the worldwide web.

Others include Rockall, the 25-metre-wide (80-foot-wide) remains of an eroded volcano nearly 500 kilometres (300 miles) off the coast of Scotland, and Surtsey, one of the world's newest islands, which belongs to Iceland and was formed by a series of volcanic eruptions in the 1960s.

Norway's Bouvet Island, deep in the South Atlantic Ocean, has an entire top level domain devoted to it, .bv, but no websites currently use it.