China pledged to step up measures to shore up its troubled banks and small businesses while continuing a crackdown on shadow banking and property speculation, in a difficult balancing act that risks exacerbating a buildup in bad debt at its traditional lenders.

As concerns mount over the state of China's $45 trillion financial system, the nation's central bank and its top financial regulator used the year's first weekend to unveil fresh details on how to combat risks amid the slowest economic expansion in three decades.

The People's Bank of China, which has been reluctant to prime the stimulus pumps too much, said Sunday that it will "resolutely win the battle" against increasing financial risks, underscoring its role as a lender of last resort while directing local governments to step up front-line support.