Trading was volatile and stocks seesawed between gains and losses, capping a tumultuous week in financial markets that saw major US equity indexes down more than 5 percent.

Statements by policy makers suggesting more action will be taken to ease the euro zone debt crisis failed to calm investors. Gold slid to a seven-week low, tumbling 6 percent, and stocks were unable to hold early gains built on comments out of Europe.

Comments from European Central Bank officials saying the ECB could provide further liquidity to the region's banking sector and speculation that the ECB may cut rates helped sentiment initially.

"Financial markets are sick and tired of the authorities in Europe and in the US twiddling their thumbs and not doing substantive things to solve this crisis of the global economy," said Barton Biggs, managing partner at New York-based Traxis Partners. "The odds of a double-dip recession on a global basis are increasing rapidly."

Investors' are concerned that authorities are unable to respond effectively to the mounting euro zone debt crisis and sluggish growth in major world economies.

A pledge from the Group of 20 finance ministers and central banks to take "all steps necessary" to calm the financial system sparked only a brief recovery in risk sentiment.

The sharp losses in gold and the spike in volatility have sparked renewed debate about whether gold remains a safe haven or functioned as a convenient place for investors to put money while stocks have struggled.

"At this point in time I don't think one can say that the safe-haven rationale for gold is off. It's just that it has been going up so much that we needed a very deep correction," said Afshin Nabavi, head of trading at MKS Finance.

By 1:15 p.m. EDT (1715 GMT), spot gold was down 6 percent at below $1,631 an ounce, after falling to a session low under $1,628. Gold has now lost almost 9 percent over two days.

Some investors saw little upside for gold, at least for now.

"The bull case for gold is on pause for the near term," said Adam Klopfenstein, senior market strategist for precious metals at Lind Waldock in Chicago.

"In the near-term, the flight-to-quality interest in owning gold is also out of the window as people are not interested in buying it even in the face of fears in the economy," he said. Until it stabilizes, I'm staying out of this market."

Global stocks as measured by the MSCI All-Country index were down 0.17 percent at 276.92 points, after earlier hitting its lowest level since July 2010 at 274.20.

The index is now in bear market territory — defined as a fall of 20 percent or more from the peak — having tumbled 23 percent from its 2011 high in May.

Wall Street shares were mixed. The Dow Jones Industrial Average was down 8.18 points, or 0.08 percent, at 10,725.65. The Standard & Poor's 500 Index was up 3.25 points, or 0.29 percent, at 1,132.81. The Nasdaq Composite Index was up 13.62 points, or 0.55 percent, at 2,469.29.

ECB Governing Council member Ewald Nowotny said it might be advisable for the ECB to add more liquidity into the banking system. The head of Germany's Bundesbank, Jens Weidmann, said the ECB has shown in the past that it can provide banks one-year liquidity when needed and could do so again if needed.

Greece denied reports that one option in its debt crisis would be an orderly default with a 50 percent haircut, while Deutsche Bank warned that European banks' write-downs on Greek bonds could exceed 25 percent.

European shares staged a late rebound, helped by a jump in banking stocks including BNP Paribas Societe Generale. The FTSEurofirst 300 index rose 0.8 percent. Emerging markets stocks slid 2.1 percent.

Crude oil futures dropped to six-week lows in volatile trading as the economic outlook remained gloomy, though some buying sparked by oversold conditions limited losses.

In London, Brent crude was off $1.10 at $104.34 a barrel after dropping to $103.43, the lowest since Aug. 10. US crude oil lost 70 cents to $79.81 a barrel.

Brent crude has fallen nearly 7 percent from a week ago, while US crude has dropped more than 8 percent.

Spot silver also fell sharply, dropping its lowest level in nearly seven months. Copper hit $7,115.75, its lowest since August 2010.

The Reuters-Jefferies CRB index, a 19-commodity global benchmark for the asset class, slipped 1.5 percent.

The euro rose 0.1 percent to to $1.3472.

US Treasuries prices slipped after a huge rally this week

Benchmark US 10-year notes were down 15/32 in price, with yields rising to 1.78 percent. Prices of 30-year bonds were down 26/32, yielding 2.84 percent.