State-run China Securities Finance Corp (CSF) will have up to $483bn (£309bn, €444bn) of money to help support the country's stock markets, which recently witnessed a rout amid falling investor confidence in the economy.

The margin financing provider has the support of the People's Bank of China (PBoC) and 17 big lenders in the country to source its financing needs, according to media reports.

China's biggest banks have lent CN¥1.3tn ($209.4bn) to CSF in order to halt the meltdown in shares, according to local media. China Merchants Bank was the biggest helper among them, lending CN¥186bn, according to financial magazine Caijing.

Meanwhile, the country's five largest banks — Industrial and Commercial Bank of China, China Construction Bank, Agricultural Bank of China, Bank of China and Bank of Communications — each contributed more than CN¥100bn.

In addition, the Chinese central bank had provided unspecified loans directly to CSF. Totally, CSF can access as much as CN¥3tn of borrowed funds from various sources, and then use the funds to buy shares and provide liquidity to brokerages, according to a Bloomberg report.

CSF's firepower is up to 25 times bigger than the support fund started by Chinese brokerages earlier in July.

The move by the government to support its stock markets comes after the Shanghai Composite index lost more than a third of its value in roughly three weeks. The index fell from a seven-year high in mid-June to hit a low point on 9 July. Nevertheless, immediate state assistance helped markets partly recover from the huge losses.

Founded in 2011, CSF is the only institution that provides margin financing loan services to qualified securities companies in China's capital market.

It "aims to facilitate the margin transactions of securities companies in market operation methods, improve China's margin transactions system, complete the functions of China's capital market, and promote the stable development of the same", according to the official website.