Japan's Nikkei 225 index had fallen sharply by lunchtime, down 2.3 percent. The broader Topix index was down slightly less, down 1.2 percent.
In China, the Shanghai and Shenzhen stock exchanges are falling, both by 0.2 percent.
The Hang Seng in Hong Kong is down 1.1 percent.
South Korea's Kospi is falling sharply, by 3 percent.
