Asian shares started the new month in the red on Monday after a court ruling threw another wrench into US tariff policy and investors braced for a reading on US jobs that could determine the course of rate cuts there.

In Hong Kong, the benchmark Hang Seng Index had a strong opening to the week, steaming up 430 points, or 1.72 percent, to open at 25,508.

On the mainland, the benchmark Shanghai Composite Index opened up 0.31 percent at 3,869 while the Shenzhen Component Index opened 0.61 percent higher at 12,773.

A holiday in the United States made for thin conditions, though Wall Street and European futures were still trading with small gains after retreating on Friday.

The US dollar and bonds were little moved ahead of a busy week for data, which includes surveys of manufacturing and services and a range of labour numbers culminating in the August payrolls report on Friday.

"Although inflation and growth data don't scream out for a rate cut, at this stage it would likely require a significant positive employment surprise to stop the Fed from moving forward, given their concern about the sharp recent deceleration in job growth," said Michael Feroli, chief US economist at JPMorgan.

The prospect of lower borrowing costs has underpinned Wall Street near record highs, and would be timely given September has been the worst performing month of the year for the S&P 500 over the past 35 years.

Early on Monday, S&P 500 futures were up 0.2 percent while Nasdaq futures added 0.3 percent. Eurostoxx 50 futures firmed 0.3, FTSE futures rose 0.1 percent and DAX futures gained 0.3 percent.

Japan's Nikkei fell 0.9 percent, tracking a drop in US tech stocks on Friday, while South Korea's market slipped 0.5 percent.

MSCI's broadest index of Asia-Pacific shares outside Japan inched down 0.1 percent, having hit a four-year high last week on the back of a bull run in Chinese stocks.

Trade uncertainty remained a drag after a US Court of Appeals ruled many of President Donald Trump's sweeping tariffs were illegal, but left them in place until mid-October awaiting an appeal to the Supreme Court.

The White House has other means to apply sectoral levies but it puts a question mark over trade agreements already reached or being negotiated. Talks with Japan have hit a stumbling block over rice, while negotiations with South Korea have bogged down.

"If the Supreme Court upholds the ruling, the Treasury would still need to return most of the now-close to US$100 billion in additional customs duties collected over the past five months, and there is a danger that other countries would back-track on any preliminary agreements," noted Paul Ashworth, chief North America economist at Capital Economics.

Investors will also be wary of Trump's attacks on the independence of the Fed this week, with Fed governor Lisa Cook set to file fresh arguments against her firing on Tuesday. A confirmation hearing for Stephen Miran, Trump's pick for another Fed position, is scheduled for Thursday. (Reuters/Xinhua)