Noting challenges posed by China and North Korea, the ministry said the regional security situation was becoming "increasingly severe at an unprecedented speed."

Japan's military budget has been rising steadily for about a decade and the ministry has already put in a request for next financial year worth $50 billion, maintaining record spending.

But Friday's request seeks to add 773.8 billion yen ($6.7 billion) in a supplementary budget for spending through March 2022, up from the record set in the year ending March 2020 of 428.7 billion yen in extra spending.

The additional money would cover the cost of missiles, patrolling aircrafts, torpedos, helicopters and other equipment, some of which were budgeted for purchase in next year's spending.

But regional challenges require Japan to "speed up the enhancement of missile defence capability and other defence capacity needed for protecting islands in the south-western region", the ministry said.

The spending request will be finalised this month after consultations with the ruling coalition, according to media reports.

In an annual defence paper released in July, Japan said US-China tensions over Taiwan are an increasingly urgent issue that threatens regional stability.

Beijing considers Taiwan part of its territory and has ramped up diplomatic, military and economic pressure on the self-governed island in recent years.

The United States has reacted strongly to Beijing's campaign, putting ally Japan in a tough position between two world powers that are both key trade partners.

But Japan has been increasingly vocal about China's maritime expansion and military build-up, publicly protesting against the presence of Chinese vessels around disputed islets known as the Senkaku by Tokyo and the Diaoyu by Beijing.

Japan's ruling conservatives have set a long-term policy goal of expanding Japan's defence budget beyond two percent of GDP, a ratio that would put it on par with NATO members

That would mark a departure from Japan's political tradition of capping defence spending below one percent of GDP, which stands around $5 trillion.

The status of Japan's military is a sensitive issue as the post-war constitution limits it to a defensive role.