Chinese state fund Central Huijin Investment bought blue-chips worth at least $41 billion in the first quarter in a bid to shore up the sliding stock market, funds' latest quarterly reports show.

The sovereign fund bought at least 300 billion yuan ($41.42 billion) of exchanged-traded funds (ETFs) in the first quarter, including Huatai-PB CSI300 ETF, E Fund CSI300 Index ETF, Harvest CSI 300 ETF, ChinaAMC CSI 300 ETF and ChinaAMC China 50 ETF, the ETFs' reports show.

The purchases helped China's CSI300 blue-chip index bounced back roughly 14% from five-year lows hit in February. The rebound was also aided by a slew of market-friendly policies and replacement of China's top securities regulator.

Central Huijin said in early February it had expanded its scope of investment in Chinese ETFs and will further increase such investment, vowing to safeguard the stable operation of China's capital markets.

The announcement came at a time when the stock benchmark CSI 300 tumbled to five-year lows as China's weak economic recovery and a lack of forceful government stimulus damped investor confidence.

Central Huijin bought 26.3 billion units of Huatai-PB CSI300 ETF in the first quarter, the fund's report on Monday shows, amounting to roughly 87 billion yuan ($12.01 billion) based on Reuters calculations.

The state fund also added roughly 73 billion yuan ($10.08 billion) of E Fund CSI300 Index ETF and 53 billion yuan ($7.32 billion) of Harvest CSI 300 ETFs, according to Reuters calculations.

Investors had suspected purchases by state institutions were helping the market.

In January, S&P Global Market Intelligence found more than $17 billion flowed to Chinese-domiciled ETFs tracking the CSI 300. Goldman Sachs also noticed heavy buying of domestic ETFs by suspected "national team" state-affiliated investors.

ChinaAMC CSI 300 ETF also saw $7.73 billion of purchase from Central Huijin, and ChinaAMC China 50 ETF saw $4.97 billion in the first quarter, their reports show.

($1 = 7.2432 Chinese yuan) (Reporting by Shanghai Newsroom; editing by Miral Fahmy)