By Jeremy Gaunt, European Investment Correspondent
LONDON, Oct 8 (Reuters) - Stock markets across the world plunged on Wednesday as concerns about the worst financial crisis in nearly 80 years and fears of a global recession gripped investors despite government efforts to intervene.
MSCI's main benchmark index of world stocks <.MIWD00000PUS> was at 4-year lows, down more than 2 percent, and its emerging market stock counterpart <.MSCIEF> fell 6.5 percent.
The pan-European FTSEurofirst 300 index <
> tumbled 4 percent and Tokyo's Nikkei share average < > plummeted 9.4 percent, the largest single-day percentage decline since October 1987.Government debt prices jumped as the equity selloff reached fever pitch and investors snatched anything resembling stability, such as gold which rose <XAU=> as much as 2 percent.
"The deteriorating outlook for the economy and the deepening financial crisis are pushing fears to their limit," said Mitsushige Akino, chief fund manager at Ichiyoshi Investment Management in Japan.
The sharp market moves came despite efforts by various authorities to inject calm and money into the battered financial system.
Britain unveiled a multibillion pound rescue package for British banks that included plans to inject up to 50 billion pounds of government money into the country's biggest operators.
It was designed to offer banks short-term liquidity, make new capital available and give the banking system enough funds to maintain lending in the medium-term.
U.S. Federal Reserve Chairman Ben Bernanke, meanwhile, warned on Tuesday that turmoil in markets could cause U.S. economic activity to be subdued into 2009 and signalled a readiness to cut interest rates.
Bernanke's sobering and candid tone about the likelihood of rate cuts came days after European Central Bank President Jean-Claude Trichet suggested last week the euro zone too could cut rates.
The Bank of England delivers its latest rate decision on Thursday and is expected to ease.
However, with the upcoming Group of Seven rich nations meeting on Friday, investors have begun to look for coordinated action to snuff out what has become a severe global threat.
YEN JUMPS, YIELDS FALL
The low-yielding yen was viewed by many currency investors as a clear favourite for relative safety.
The dollar dropped at one point below 100 yen to 99.60 yen <JPY=> but was later down 0.5 percent at 100.84 yen. Britain's pound <GBP=> gained around half a percent on the bank plan to $1.7569.
"Investor risk aversion and selling of high-yielding currencies are prominent," said Masafumi Yamanoto, head of foreign exchange strategy for Japan at Royal Bank of Scotland.
In another sign of risk aversion, the Markit iTraxx Crossover index <ITEXO5Y=GF>, made up of 50 mostly "junk"-rated Euroepan credits, was at 632.5 basis points, according to data from Markit, 16 basis points wider than late on Tuesday.
Investment flowed into government bonds, pushing yields lower.
Interest rate-sensitive two-year Schatz yield <EU2YT=RR> was down 13 basis points at 3.040 percent. (Editing by Mike Peacock)