TOKYO (AFP, BLOOMBERG, REUTERS) - Japan is considering amassing an arsenal of more than 1,000 of its planned long-range missiles, the Yomiuri newspaper reported on Sunday (Aug 21), citing unidentified sources.

The projectiles, which have a range of 500km to 5,500km, will be deployed mainly across the Nansei Islands and Kyushu, according to the article.

By doing so, Japan is seeking to close the "missile gap" with China, which has about 300 sea-based and 1,900 land-based missiles, according to the newspaper.

Japan embarked on a programme a few years ago to boost its missile capabilities in the face of potential threats from China and North Korea.

The latest report on the scale of a potential Japanese stockpile follows China's recent military exercises in waters and airspace around Taiwan after US House Speaker Nancy Pelosi visited the island.

Japan is also planning to upgrade and extend the capability of its domestically produced Type 12 surface-to-ship missile deployed by the Ground Self Defence Force to hit objects more than 1,000km away, Yomiuri reported.

That would be enough to reach Chinese coastal areas as well as North Korea, the newspaper reported, citing unnamed sources.

Upgrades would also need to be made to allow Japan's existing ships and aircraft to be able to fire the new missiles, which could hit land-based targets, the newspaper reported.

Japanese officials could not immediately be reached for comment on the issue.

Japan interprets its war-renouncing post-war Constitution to mean it may use its military only for self-defence.

The country has stepped up its military spending and taken a more assertive strategy in recent years. But it has refrained from deploying long-range missiles, among its limits on weapons that can strike targets on foreign soil. 

Recent geopolitical tensions, including Russia's invasion of Ukraine, have prompted growing calls in Japan to review its defence programmes.

Mrs Pelosi's visit to Taiwan earlier this month also ratcheted up regional tensions. 

China launched missiles near Taiwan and into Japan's exclusive economic zone in response to her visit.

Beijing regards Taiwan as a renegade province awaiting reunification with the mainland, by force if necessary. 

Japanese Prime Minister Fumio Kishida has vowed to significantly boost defence spending, which has been kept close to around 1 per cent of gross domestic product.

Local media also reported that Japan’s defence ministry is likely to request 5.5 trillion yen (S$55.9 billion) for the next fiscal year, up slightly from the 5.18 trillion requested for the current fiscal year.

But the ministry was also expected to ask approval for a list of unpriced items, including the development cost to upgrade the long-range cruise missiles, the Asahi Shimbun newspaper said.