ZURICH (AFP) ― The Bank for International Settlements warned Sunday that global financial markets appeared to be increasingly fragile despite bullish sentiment.

The Basel-based institution, considered the central bank for central banks, also voiced concern in its quarterly report about the impact of the rising U.S. dollar and falling oil prices, particularly on emerging economies.

Claudio Borio, the head of the BIS monetary and economic department, highlighted events in mid-October when stock prices fell sharply and U.S. Treasury bonds were “exceptionally volatile” ― even more than at the height of the crisis triggered by the collapse of Lehman Brothers in 2008.

“And yet, just a few days later, the previous apparent calm had returned.”

“To my mind, these events underline the fragility ― dare I say growing fragility ― hidden beneath the markets’ buoyancy,” he said.

Global stocks are surging on hopes that the world’s biggest economy is recovering, with a surprisingly robust U.S. jobs report for November powering Wall Street to record highs last week.

The dollar has also strengthened against the euro and the yen, as the central banks of the single European currency zone and Japan push interest rates to record lows to chase an elusive growth.

At the same time, oil prices have slumped by 40 percent since June because of oversupply ― the third largest fall in the last 50 years.

The prices of other commodities were also showing drops.

Borio said the diverging developments are expected to “leave a profound imprint on the financial and macroeconomic scene.”

Emerging market economies expected to be hardest hit because “the outsize role that commodities and international currencies play there makes them particularly sensitive to the shifting conditions,” he said.

Emerging economies have racked up to $3.1 trillion in dollar-denominated debt by mid-2014.

A continued appreciation of the dollar would therefore increase debt burdens, Borio said.

At the same time, some of these economies are dependent on commodity exports and have therefore come under intense pressure over falling prices.

A stormy meeting of the 12-member OPEC cartel last month demonstrated the painful impact of the slumping prices, with Venezuela and Nigeria pleading for output to be slashed.

A day after OPEC decided to maintain its output target, Venezuelan President Nicolas Maduro’s government announced painful budget cuts.

Non OPEC-member Russia has also said it is losing up to $100 billion a year because of the oil price slump.