WASHINGTON (AFP) - Another bout of unnerving global panic-selling erupted Monday, with some markets recording their largest one-week losses since 2008, raising fresh worries over the strength of the global economy and yet another financial crisis.

While analysts said a repeat of the 1997 or 2008 crashes was not in the cards - mainly because of reforms undertaken since - they warned that continued turbulence emanating from China would take a toll on global economic growth, especially in emerging economies.

After an 8.5 per cent plunge in Shanghai shares Monday, investors dumped stocks across nearly all markets, with the main US and European exchanges repeating Friday's losses with drops of 3.6-5.4 per cent, wiping out any profits earned over the past year.

The carnage was even worse in emerging economies, spurring comparisons to the 1997 financial crisis, which left East and Southeast Asian economies in tatters and some seeking bailouts from the International Monetary Fund.

At that time, China was a rock of stability. This time, it is the source of the turmoil.

Beijing's failed efforts to calm its own capital markets and stem the domestic economic slowdown were compounded by the unexpected devaluation of the yuan two weeks ago.

That sparked a wholesale outflow of capital not only from China but from most emerging economies and, effectively, a bout of competitive devaluations.

Weeks later, the worries that leaders in Beijing have not yet got a handle on the country's economic problems have only grown.

"What we are facing now is the increasing uncertainty over the ability of the Chinese authorities to manage the transition in China," Angel Ubide, an economist at the Peterson Institute for International Economics, told AFP.

The failed market interventions, he said, have only increased questions "about whether the Chinese authorities are really on top of things."

Already amid worries about China and other emerging economies, the IMF in July cut its 2015 growth forecast for the year to 3.3 per cent from 3.5 per cent predicted just three months earlier.

Another downgrade could come, economists say, but mainly from ongoing problems in other emerging markets that are exacerbated by China's woes.

Charles Collyns, an economist at the International Institute of Finance in Washington, called the market turbulence "a classic uncertainty shock that has a maximum impact in the short term."

"I do think that there are enduring factors that do imply a more enduring impact on the global economy. I don't think you can just shrug your shoulders and say, don't worry, come back in two weeks," Collyns said.

"There is a broader malaise across emerging markets," he said, pointing to the political crises in Brazil and Turkey, stalled reforms in India, the impact of sanctions on Russia, and the loss of income in oil exporters like Nigeria.

Even so, Collyns and other analysts were quick to dismiss the suggestion of another global financial crisis in the air.

After the 1997 Asian upheaval, emerging economies freed up their currencies and capital markets, and their companies stopped depending excessively on what were once cheap dollar loans.

"Back then, the whole house of cards came down. But today, with no pegs, the exchange rates are able to take some of the local heat, like a safety valve," said Song Seng Wun, an economist with CIMB Private Banking.

As for Japan, Europe and the United States, the sources of the problems in the 2008 crisis - the banks - have gone through rigorous reforms and recapitalization that leave them far more able to handle upheavals.

And central banks in all three remain on crisis footing, holding interest rates close to zero and, in Japan and Europe, still pumping liquidity into their economies to bolster growth.

Since 2008, trillions of dollars in respective currencies have been injected into economies to shore up banks and spur spending, investment, and job creation.

"We've long felt that the only thing preventing another financial crisis has been extraordinary central bank liquidity and general interventions from the global authorities which we still expect to continue for a long while yet," Jim Reid, head of fundamental credit strategy at Deutsche Bank, said in a note to clients.

The support could easily continue if growth slows further. Tokyo and Frankfurt could expand their quantitative easing programs; Beijing could add to growth support; and the Federal Reserve could easily put off a planned interest rate hike.

Indeed, said Stephen Oliner, an economist with the American Enterprise Institute and a former Fed staffer, "With the plunge in global markets, I think it's unlikely that the Fed will raise rates in September" as had been expected.

Ubide argued that any talk of fresh central bank action outside of China is premature.

"It looks scary, no question. But this is when central banks have to show their steady hand and keep calm," Ubide said.

"What they should do is wait to see how long this lasts, what the situation is in two or three weeks, and then react."