Hong Kong stocks slumped again Thursday following a seven percent collapse in mainland markets that caused trading to be suspended after just 30 minutes as China weakened its yuan-dollar value to a five-year low.

The benchmark Hang Seng Index slipped 3.09 percent, or 647.47 points, to close at 20,333.34 -- it has lost more than seven percent in its four trading days this year.

In Shanghai the composite Index closed down 7.04 percent, or 236.84 points, at 3,125.00 and the Shenzhen Composite Index, which tracks stocks on China's second exchange, tumbled 8.24 percent, or 175.87 points, to 1,958.09.