BEIJING / NEW YORK - China may have to press ahead with new tightening policies to combat its inflationary pressures in light of the United States' downgraded credit rating and fears that the US government will enact a new round of monetary loosening measures, analysts said.

"China, which is tackling its inflation, will face more complicated challenges if the US launches (a third round of quantitative easing policy)," said Tang Min, an economist at Peking University. "The government is very likely to resort to more tightening monetary policies in the second half of this year, such as increasing interest rates and the reserve requirement ratio to fight against inflation. Investors can expect further action from policymakers to contain prices."

Oliver Barron, a financial analyst at London-based brokerage house North Square Blue Oak, said that uncertainty over the US economy and fears of a new round of stimulus measures by the US may prompt China to increase the amount of renminbi it prints every month to buy foreign currency from the banking sector. China increased its money supply in response to the US' second round of stimulus measures, called QE2, late last year.

"The central bank accelerated the pace of renminbi appreciation against the dollar in September 2010 before QE2, and may be forced to do so again now to combat new inflationary pressures," Barron said.

With the US Federal Reserve set to hold its regular discussions on Tuesday over interest rates and other monetary policies, some analysts believe the Fed will announce a fresh round of measures to shore up its ailing economy.

US economist Nouriel Roubini said that a QE3 is inevitable "in the context of a widening output gap in the first half, a broad-based stall of employment growth and forthcoming increasing drag from fiscal policy."

"It's too soon to go to something like a full scale QE3, but it's not too soon to signal concern," John Richards, head of strategy at RBS Americas, told Reuters. "If you lengthen the perception in the market's mind of how long rates are going to stay low ... that pulls down long-term rates as well," he said.

China will announce its July consumer price index (CPI) data on Tuesday but indicators show that inflationary pressures may persist in the short term.

A report from Goldman Sachs said China's CPI, the main gauge of inflation, may stay around 6.5 percent in July due to soaring food prices.

China's inflation was at 6.4 percent year-on-year to a three-year high in June, well above 5.5 percent in May. To curb inflation, the central bank has raised interest rates three times and increased the reserve requirement ratio for commercial lenders by 50 basis points.

Despite the US' bipartisan consensus to raise the country's debt ceiling by $2.4 trillion and cut the deficit by $2.1 trillion over a decade, the Standard & Poor decided to cut the long-term US credit rating to AA+, citing concerns about the government's budget deficit and worsening debt prospects.

Earlier, a major Chinese rating agency, the Dagong Global Credit Rating Co, downgraded the US' sovereign credit rating from A+ to A. Raising the debt cap does improve the US' worsening debt problems and does not improve Washington's ability to repay its debts, the Beijing-based company said.

China has a major stake in the future of the dollar as analysts estimate that about 70 percent of its $3.2 trillion in foreign reserves is invested in dollar assets, making it the US' biggest foreign creditor.

Zhou Xiaochuan, governor of the People's Bank of China, the central bank, urged the US to handle its debts responsibly to ensure the safety of Chinese investment in a statement.

China will continue to "diversity its foreign exchange reserve investment and enforce management of risks, in order to reduce negative impacts from any fluctuations in international financial market," he said.

Zuo Xiaolei, chief economist at China Galaxy Securities, said China's foreign exchange purchasing power will drop substantially as a result of the dollar depreciation and China's rising inflation.