Tokyo's benchmark index dived nearly 4.0 percent at the close Tuesday, hitting a fresh six-month low and erasing a morning rebound, as Hong Kong and Shanghai extended losses on worries over China's growth.

In wild trading, the Nikkei 225 at the Tokyo Stock exchange ended 733.98 points lower at 17,806.70 -- its sixth-straight losing session and the lowest finish since mid-February -- after briefly clawing back into positive territory by the midday break.