Chinas Zentralbank hat in einem historischen Schritt die Zinsen leicht angehoben, um die Konjunktur ein wenig zurechtzustutzen: China's central bank raised official borrowing costs for the first time in nine years Thursday night, a step aimed at slowing breakneck economic growth and inflation but one that could risk social unrest if heavily indebted state companies respond by laying off more workers. Beijing also removed the ceiling on what banks could charge for loans, a measure that paradoxically could make more loans available to risky private enterprises and ultimately enhance China's long-term growth prospects and give its economy much greater stability. The two moves shift China further toward a Western-style financial system in which markets determine the allocation of credit, not government officials. The interest rate increase, a little more than a quarter of a percentage point, is not big enough by itself to change the direction of the Chinese economy. But it is widely expected by economists to be the first in a series of increases that could lift rates by as much as two percentage points in the coming year, which could seriously curtail economic growth. That would damp demand for products offered by the United States and other countries rushing to take advantage of the Chinese market. But the effect on American consumers is likely to be quite small, as Chinese companies are expected to take the steps needed to keep prices low and maintain their exports. For Beijing, the interest rate increase is a historic embrace of free-market tools of economic management despite possible internal political repercussions, said Tao Dong, the China economist at Credit Suisse First Boston's office here.