With markets roiled by concerns over China Evergrande Group's debt issue, China's central bank net injected the most short-term cash into the financial system in eight months.

With seven- and 14-day reverse repurchase agreements, the People's Bank of China put in 110 billion yuan ($17 billion) of cash. That was the biggest increase in open-market operations since late January when a funding shortage drove up interbank rates. The PBOC had injected liquidity for three straight sessions before Thursday, fanning speculation that Beijing is attempting to calm market worries over Evergrande.

Concerns over Evergrande's ability to meet its obligations have spilled over into global markets, necessitating assistance to calm market jitters. The focus is on whether the developer can pay $83.5 million in interest on a five-year dollar bond due Thursday. The coupon is part of $669 million in bond interest due through the end of the year, with a 30-day grace period before a missing payment is considered a default.

In early trading Thursday, the indebted developer's Hong Kong-listed shares rose as much as 32 percent, the biggest since 2009, hoping that the business would avoid a chaotic debt resolution after one of its units negotiated interest payments on yuan bonds.

Apart from attempting to assuage market fears over Evergrande, regulators lessen their hold on liquidity as the quarter progresses, owing to a growing need for cash from banks for regulatory checks. Lenders will also need to save more money in preparation for the one-week holiday at the beginning of October.