Chinese shares edged down 0.52 percent on Tuesday, trailing the downward trend of the previous two trading days, amid thin trading volume.

The benchmark Shanghai Composite Index fell 0.52 percent, or 12.88 points to end at 2,457.2. The Shenzhen Component Index closed at 8,192.8 points, up 22.65 points, or 0.28 percent.

Aggregate turnover on the two bourses sharply shrank to 48.22 billion yuan ($7.03 billion) from 69.77 billion yuan on the previous trading day. Losses outnumbered gains by 552-304 in Shanghai and 422-285 in Shenzhen.

The Shanghai Composite Index opened at 2445.22 points and touched a new intra-day low of 2430.85. The key index briefly gained ground in sync with the release of the lower-than-expected monthly consumer price index (CPI) data in the morning.

CPI, a main inflation gauge, was up 6.3 percent in July year on year, the National Bureau of Statistics announced on Tuesday, lower than the 7.1 percent in June and 7.7 percent in May.

The steel sector boosted the index with Baosteel, the country's largest steel maker, up 2.6 percent to 7.11 yuan. Shenzhen-listed Angang Steel Co., Ltd. jumped 5 percent to 10.29 yuan after it reported on Tuesday a 24.48 percent year-on-year net profit increase to 5.98 billion yuan in the first half.

However, the market failed to sustain momentum in the afternoon session as Olympic and securities shares led the decline.

Olympic-theme stocks continued to drag down the index on profit taking, dealers said, with Beijing Capital Tourism Co down 10.01 percent to 16.55 yuan and Beijing Xidan Department Store down 9.98 percent to 9.92 yuan.

Securities shares fell across the board, spurred by shrinking income expectation from brokerage business amid sluggish trading, dealers said.

The Shanghai Stock Exchange touched a 21-month low on Tuesday with a daily trading volume of less than 32 billion yuan.

CITIC Securities, the country's largest listed broker, shed 8.03 percent to 17.99 yuan as the Beijing-based company has 987.35 million non-tradable shares to be unlocked on August 15. Another major brokerage firm, Haitong Securities, plummeted 10.02 percent to 17.43 yuan.