Stocks were mixed on Wednesday as investors assessed Donald Trump's latest tariff threats, while keeping an eye on trade talks after the US president warned he would not again extend a deadline to reach deals.

In Hong Kong, the benchmark Hang Seng Index ended the day at 23,892, down 255 points or 1.06 percent. The Hang Seng China Enterprises index fell 1.28 percent to 8,597.

Up north, the benchmark Shanghai Composite Index closed down 0.13 percent at 3,493 while the Shenzhen Component Index closed 0.06 percent lower at 10,581.

The ChiNext Index, tracking China's Nasdaq-style board of growth enterprises, gained 0.16 percent to close at 2,184.

US President Donald Trump said said he would impose a 50 percent tariff on imported copper and soon introduce long-threatened levies on semiconductors and pharmaceuticals, broadening his trade war that has rattled markets worldwide.

Trump also said trade talks have been going well with the European Union and China, though he added he is only days away from sending a tariff letter to the former.

"We have had a really good relationship with China lately, and we're getting along with them very well. They've been very fair on our trade deal, honestly," Trump said, adding that he has been speaking regularly with President Xi Jinping.

"It may boost market sentiment in the short term," said Deng Lijun, analyst, Huajin Securities.

"The new wave of tariff increases did not involve China, and the United States had lifted export restrictions to China for chip design software developers and ethane, and Sino-US trade tensions have eased in the short term," Deng said, adding that risk appetite for A-shares may rebound once Beijing and Washington reach a tariff deal.

Around the region, MSCI's Asia ex-Japan stock index was weaker by 0.42 percent, while Japan's Nikkei index closed up 0.33 percent. (Agencies)