Japan's powerful lower house of parliament on Friday passed a record $793 billion budget, including fresh economy-boosting stimulus and more defence spending as Tokyo eyes an increasingly assertive China.

The government plans to spend 96.34 trillion yen for the fiscal year to March 2016 under the budget which will now be sent to the upper house for final approval. Passage is expected within several weeks despite possible opposition moves to stall the bill.

Tokyo's spending package is aimed at reversing an expected 0.5 percent contraction in the world's number three economy for the current fiscal year that ends this month.

But the eye-popping budget will also inflate a huge national debt that is already twice the size of the economy -- one of the biggest burdens among wealthy nations.

Among the spending is 5.97 trillion yen for public works, while other funds will pay for programmes such as child-care and medical assistance which are aimed at luring more women into the workforce, a key part of Prime Minister Shinzo Abe's bid to stimulate the long-tepid economy, dubbed Abenomics.

Japan's defence spending will also set a record at 4.98 trillion yen as the hawkish Abe looks to strengthen surveillance of territorial waters amid ongoing diplomatic battles with Beijing over the ownership of islands in the East China Sea.

Almost one-third of the budget is for social security programmes, estimated to cost a record 31.53 trillion yen, up 3.3 percent from the fiscal 2014 budget and underscoring how Japan's rapidly ageing population is straining the public purse.

One quarter of the package will cover Tokyo's debt-servicing costs with plans to issue fresh bonds worth 36.9 trillion yen to help pay for the increased spending.