* Benchmark yields fall below 2.75 percent to 2-month lows
* Longer-dated yields on track for 4th week of decline
* Fed to buy $2.50-$3.50 billion Treasuries due 2019-2020
NEW YORK, Jan 24 (Reuters) - U.S. Treasuries prices rose on Friday with benchmark yields hitting near two-month lows on safe-haven bids for bonds stemming from worries about tightening credit conditions in China and a looming currency crisis in Argentina.
Those worries since Thursday have spurred selling in global stock markets and other riskier investments as investors scrambled into the relative safety of cash and U.S. and German government debt.
"Investor sentiments have felt fragile. Things are spiraling a bit here," said David Keeble, global head of interest rate strategy at Credit Agricole Corporate & Investment Bank in New York.
Beijing's effort to rein in its unhealthy growth in high-risk lending has stoked concerns about how that might impede expansion of the world's second largest economy.
Argentina meanwhile abandoned support of its currency on the open market this week, resulting in the peso's biggest drop since the 2002 financial crisis. Although chances of Argentina's woes rippling across Latin America are remote, investors are worried this could hurt the currencies of Argentina's major trade partners.
Safety bids for Treasuries stemming from concerns about China and emerging markets were mitigated by caution ahead of next week's $111 billion in longer-dated U.S. government debt supply and the Federal Reserve's two-day policy meeting, analysts and traders said.
Benchmark 10-year Treasuries notes were up 11/32 in price with a yield of 2.735 percent, down 4 basis points from late on Thursday. The 10-year yield fell to 2.706 percent earlier, which was below its 100-day moving average and the lowest intraday level since Nov. 26, according to Reuters data.
Ten-year and 30-year yields were on track on for four straight weeks of decline, a move which have not happened since last March to early April.
On Wall Street, the three major stock indexes stumbled for a second straight day with the Standard & Poor's 500 index falling 0.6 percent.
The bond market was also supported by the upcoming bond purchase from the Fed for its bond-purchase stimulus program. The central bank planned to buy $2.50 billion to $3.50 billion in U.S. government debt that matures Oct. 2019 to Dec. 2020 for its third round of quantitative easing at 11 a.m. (1600 GMT).
Fed policy-makers will meet next Tuesday and Wednesday and consider whether to further scale back QE3 that is aimed at holding down long-term borrowing costs to help the economy.
In December, the Federal Open Market Committee pared its monthly purchases of Treasuries and mortgage-backed securities by $10 billion to $75 billion in January. The Fed's policy-setting group is expected by some analysts to cut its monthly purchases by another $10 billion at its upcoming meeting.
"The upside potential for the market is limited with the FOMC and supply coming," said Thomas di Galoma, co-head of fixed-income rates at ED&F Man Capital in New York.
He expected the 10-year yield would face resistance in the 2.65 percent area.