Mainland and Hong Kong stocks extended declines on Tuesday with weakness across the board, joining the slide in the Asia region as sentiment turned jittery ahead of a slate of US data releases.

In Hong Kong, the benchmark Hang Seng Index was down 393 points, or 1.54 percent, at 25,235, the Hang Seng Tech Index was down 95 points, or 1.74 percent, at 5,402 and the Hang Seng China Enterprises Index was down 159 points, or 1.79 percent, at 8,757.

The benchmark Shanghai Composite Index was down 43 points, or 1.11 percent, at 3,824 while the Shenzhen Component Index was 197 points, or 1.51 percent, lower at 12,914 and the ChiNext Index, tracking China's Nasdaq-style board of growth enterprises, was 66 points, or 2.1 percent, down at 3,071.

The blue-chip CSI 300 Index lost 1.2 percent at the close after briefly touching a three-week low earlier in the session.

The combined turnover of the Shanghai Composite and the Shenzhen Component indexes was 1.72 trillion yuan, down from 1.77 trillion yuan on Monday.

Stocks related to retailing, education, digital currency and autonomous driving led gains while those related to precious metals, controlled nuclear fusion, cultivated diamonds and non-ferrous metals led losses.

Weakness was across the board on Tuesday. The rare-earth sector led losses with a 2.9 percent drop, new energy-related shares lost 2.4 percent, and the artificial intelligence sector declined 2.5 percent amid concerns about the sector being overheated.

Sentiment has turned cautious again after latest economic data showed domestic fundamentals remain weak, and with key policy meetings for the year mostly concluded last week, the market will need more forceful catalysts if it was to grind higher, analysts at Nanhua Futures said.

"We think the market is likely to continue range-bound for the near term," and the US data release this week could add to volatility if they impact rate cut expectations, they added.

Lifting the broader markets on Tuesday, the CSI Intelligent Vehicle Index climbed 0.4 percent after regulators approved for the first time two Chinese cars with level-3 autonomous driving capabilities.

Around the region, sentiment was fragile with shares tumbling as investors adopted a cautious approach ahead of US data. (Reuters/Xinhua)