LONDON -- Financial markets around the world were roiled Thursday after Japanese stocks suffered their biggest slide since the country was hit by a devastating tsunami more than two years ago.

Several reasons have been blamed for the 7.3 per cent fall in the Nikkei index to 14,483.98, including a spike in the Japanese government's borrowing costs and unexpectedly weak Chinese manufacturing figures.

Mixed messages from the U.S. Federal Reserve about when it may start easing the amount of financial assets it purchases each month have also contributed to Thursday's retreat.

Wednesday's written testimony to lawmakers in Congress from Fed chairman Ben Bernanke appeared to signal that the central bank was not yet ready to change its policy of flooding the economy with money by buying up bonds from banks. However, Bernanke's subsequent comments -- and the minutes of the Fed's last rate-setting meeting -- triggered speculation that change is afoot.

Much of the recovery in global stock markets over the past few years has had its roots in the extra money that's been recycled through financial markets. This extra liquidity has come from the stimulus initiatives by a number of the world's leading central banks. The withdrawal of some of the Fed's stimulus measures has been seen as the greatest threat to stocks for some time.

"The mood has switched from greedy to fearful," said Chris Beauchamp, market analyst at IG.

In Europe, the FTSE 100 index of leading British shares, which was only around 75 points off its highest-ever close on Wednesday, was down 2 per cent at 6,699. Germany's DAX, which has hit a series of all-time highs recently, tumbled 2.5 per cent to 8,312 while the CAC-40 in France was 2.2 per cent lower at 3,951.

In the U.S., the Dow Jones industrial average was down 0.6 per cent at 15,222 soon after the open, while the broader S&P 500 index fell 1 per cent to 1,638. U.S. markets have not had a two-day losing streak for around a month, clear evidence of the optimism that has gripped investors.

Those declines though are dwarfed by the scale of the reverse in Japan's Nikkei, the biggest since March 2011. Some sort of decline in global indexes, especially in the Nikkei, had been anticipated following a run that's seen many post historic highs.

"The fact that the equity markets fell so hard on these headlines overnight indicates that perhaps investors have been guilty of too much exuberance in recent months," said Jane Foley, an analyst at Rabobank International.

The Nikkei has been the best-performing major index this year, having risen around 45 per cent -- before Thursday's loss -- to five-year highs. The index has been buoyed by the announcement of an aggressive monetary stimulus from the Bank of Japan, which has piled the pressure on the yen. That development is a potential boon to the country's exporters and therefore to growth -- a favourable backdrop for stock investors.

Many in the markets blamed the Nikkei's fall on the spike in the interest rate charged on country's benchmark 10-year bond to above 1 per cent for the first time in a year. That unnerved investors at a time when Japan's already overburdened government finances are vulnerable to rises in interest rates. The interest rate, or yield, later slipped back to about 0.9 per cent.

The sell-off is a reminder of Japan's vulnerability as Prime Minister Shinzo Abe tries to end two decades of stagnation with unprecedented monetary easing, increased government spending and reforms to make the world's No. 3 economy more competitive.

The level of Japan's debt is higher, relative to its economy, than even some of the crisis-stricken European countries. But because it is mostly owned by domestic investors, especially huge banks and insurance companies, the country's credit rating has remained steady. About a quarter of the national budget is interest payments on government debt.

Markets elsewhere in Asia sank sharply after a survey showed China's manufacturing contracted in May. HSBC said its preliminary Purchasing Managers Index fell to a seven-month low of 49.6 in May from April's 50.4. Numbers below 50 indicate that activity is contracting. Analysts had expected a more modest decline to 50.3.

The Shanghai Composite Index lost 1.2 per cent to 2275.67, its biggest fall in a month while the smaller Shenzhen Composite Index shed 0.7 per cent to close at 1014.47.

Elsewhere, Hong Kong's Hang Seng slumped 2.5 per cent to 22,669.68. South Korea's Kospi lost 1.2 per cent to 1,969.19. Australia's S&P/ASX 200 dropped 2 per cent to 5,062.40.

There were big moves across a range of financial assets. In the currency markets, the yen was the main mover following the rise in Japanese yields. The yen has bounced back strongly, after falling to near five-year lows against the dollar on Wednesday. The dollar was trading 1.6 per cent lower at 101.48 yen, having earlier fallen to a low of 100.86 yen.

Oil prices were under the kosh too amid concerns over the global growth environment -- the benchmark New York rate was down $1.61 at $92.67 a barrel. Gold, however, was in demand as it benefited from its status as a haven at a time of uncertainty. It was up 1.4 per cent at $1,387 an ounce.

The main debate now in the markets is whether Thursday's developments mark the end of the euphoria that has gripped many investors this year.