BEIJING (AP) — The Moody's ratings agency on Monday cut China's credit rating due to surging debt, prompting a protest by Beijing and highlighting challenges faced by communist leaders as they overhaul a slowing economy. Private sector analysts say it could drag on the economy or threaten the health of the state-owned banking industry. The government is trying to make the economy more productive by giving market forces a bigger role and "supply side reform," or shrinking bloated industries such as steel and cement in which supply exceeds demand, which has depressed prices and led to financial losses. The finance ministry noted the growth rate ticked up to 6.9 percent in the quarter ending in March and said tax revenue rose 11.8 percent in the first four months of the year. The importance the authorities attach to maintaining robust growth will result in sustained policy stimulus, given the growing structural impediments to achieving current growth targets.