* CSI300 -1.8 pct; SSEC -2.1 pct; HSI -1.8 pct
* China's outstanding margin loans shrink for 16 days in a row
* Index heavyweights Sinopec, PetroChina and CNOOC tumble
SHANGHAI, Jan 26 (Reuters) - China and Hong Kong stocks fell on Tuesday as slides in global equity markets and oil prices resumed, rattling investors.
The CSI300 index fell 1.8 percent to 3,074.10 points by the end of the morning session, while the Shanghai Composite Index lost 2.1 percent, to 2,877.11.
In Hong Kong, the Hang Seng index dropped 1.8 percent, to 18,984.58, while the Hong Kong China Enterprises Index lost 2.5 percent, to 7,968.85.
Chang Chengwei, an analyst at brokerage Hengtai Futures, said that the China market is still struggling to find a bottom, with many investors staying out of the market after two sharp sell-offs in six months.
"Volume is getting very thin, as there is hardly any fresh inflows, and the process of deleveraging is continuing," Chang said.
China's outstanding margin loans - money investors borrow to buy stocks - had declined for 16 consecutive sessions until Jan. 22, the longest losing streak on record, with 209.3 billion yuan ($31.81 billion) worth of leveraged bets unwound during the period.
The market was little fazed by Premier Li Keqiang's comments that the government would expand tax reforms to aid the struggling economy.
All stocks in China and Hong Kong fell, with energy shares slumping in both markets on lower oil prices.
Chinese oil giant PetroChina slumped 4.8 percent in Hong Kong and fell 2.3 percent in China.
Two other Hong Kong-listed oil majors, Sinopec and CNOOC, tumbled over 6 percent. ($1 = 6.5795 Chinese yuan renminbi)
Reporting by Samuel Shen and Pete Sweeney; Editing by Kim Coghill