SYDNEY (BLOOMBERG) - Asian stocks declined on the final trading day of the month as President Donald Trump's plans to impose new tariffs on China and renewed turmoil in emerging markets weighed on investor sentiment.

Stocks slipped from Tokyo to Hong Kong after the S&P 500 declined as Trump was said to be moving ahead with a new trade plan as soon as next week. Emerging-market equities remained under pressure and currencies declined, with the Bank of Indonesia intervening to contain the knock-on effect of weakening currencies in Argentina and Turkey on the rupiah.

Japan's Topix index fell 0.3 per cent as of 10:15am in Tokyo. The Shanghai Composite lost 0.3 per cent while Hong Kong's Hang Seng Index slipped 1.3 per cent.

South Korea's Kospi index slid 0.2 per cent and Australia's S&P/ASX 2000 dropped 0.1 per cent.

Futures on the S&P 500 Index were down 0.1 per cent.

Caution is creeping into markets as global stocks round out a month that's seen a strong rally from mid-August. While the US Federal Reserve remains on its tightening path and Chinese authorities have moved to loosen policy and stem declines in its currency, the threat of global growth being hit from a souring of US-China relations remains front and centre. There's also the deepening turmoil in Argentina and Turkey.

On trade, the US president wants to move ahead with a plan to impose tariffs on US$200 billion in Chinese imports as soon as a public-comment period concludes next week, according to people familiar with the matter.

Elsewhere, crude pared gains though remained above US$70 a barrel after breaking through for the first time in a month as shrinking stockpile levels in the US pointed to supply constraints. Declines at Tencent weighed on shares in Hong Kong after China proposed restrictions on games.