SHANGHAI — China announced a move on Saturday aimed at addressing a vexing problem: how to steer more bank loans to small businesses while adding little to the country’s huge debt load.

A little more than a week ago, Standard & Poor’s downgraded China’s sovereign debt rating and its ratings on many Chinese financial institutions, citing a steep expansion in credit. But more than half of that lending has been to state-owned businesses, many of which are chronic money losers but provide so many jobs that, politically, they are almost impossible to close.

Yet even as steel mills, aluminum smelters, cement factories and other big enterprises have gorged on debt, small businesses have struggled to find the money they need to expand.

The People’s Bank of China, the country’s central bank, tried to address that on Saturday with a complex adjustment to a crucial regulation for commercial banks.