Japan warship asserts right to sail through Taiwan Strait — media

There was no immediate confirmation from the defense ministry of the passage, which the reports said took place on Wednesday, following similar journeys by US and European navies in recent years.

Beijing views Taiwan as a renegade province and claims jurisdiction over the body of water that separates the island from China.

The United States and many other countries argue such voyages are usual, citing freedom of navigation.

Washington and its allies have lately increased their crossings of the 180-kilometre (112-mile) Taiwan Strait to reinforce its status as an international waterway, angering Beijing.

Earlier this month, China accused Berlin of heightening security risks in the Taiwan Strait, a day after two German military vessels sailed through the waters.

Japan is a key US ally, and its reported first sailing in the Strait comes after Tokyo in August slammed what it called the first confirmed incursion by a Chinese military aircraft into its airspace as a "serious violation" of its sovereignty.

The Yomiuri Shimbun daily, citing unnamed government sources, said that Prime Minister Fumio Kishida had instructed the move due to concern that doing nothing following China's intrusion into Japanese territory could encourage Beijing to be more assertive.

Earlier this month, a Chinese aircraft carrier sailed between two Japanese islands near Taiwan for the first time.

Tokyo called the incident "totally unacceptable", while China said it had complied with international law.

Beijing has said it would never renounce the use of force to bring Taiwan under its control, with Chinese leader Xi Jinping in recent years upping the rhetoric of "unification" being "inevitable".

In response, Taiwan has strengthened economic and political ties with its allies -- most notably the United States, its biggest weapons provider -- while increasing its defence budget.

The reported sailing comes as Kishida's ruling party holds a party leadership election on Friday that will be a de facto vote to decide Japan's next prime minister.

Candidates in the race have been debating a range of issues, including diplomacy and security in response to China's growing military clout in the region.

Because the conservative Liberal Democratic Party holds a parliamentary majority, the winner is certain to become prime minister, and will likely call a snap election to shore up their mandate.