Japanese shares plunged more than 14 percent on Tuesday as fresh explosions rocked a damaged nuclear plant and triggered a rise in radiation levels, sending investors fleeing from riskier assets such as equities and commodities across Asia.

The benchmark Nikkei 225 stock index extended its early slump after Prime Minister Naoto Kan said radiation levels at the plant on the northeast coast had risen and urged people within a 30-km (18 mile) radius of the facility to stay indoors.

One report said minute levels of radiation had been detected in Tokyo.

So far this week, $720 billion in market value has been wiped off the Tokyo stock exchange's biggest companies in the wake of a massive earthquake and tsunami which hit the country on Friday, triggering the nuclear crisis.

The dollar soared to just above 82.00 yen on trading platform EBS from near 81.40 before settling back to near 81.65 yen, little changed on the day and not far from a record low of 79.75 struck in 1995.

Asian currencies from the Australian dollar, the New Zealand dollar to the Thai baht, with the Aussie dropping more than 1 percent on the day to a session low at $0.9986.

All focus is on the nuclear crisis. In the situation where the crisis appears to be worsening, foreign investors and domestic fund operators are pulling out from Japanese shares, Hideyuki Ishiguro, a supervisor at Okasan Securities in Tokyo.

Asian share markets had initially posted modest losses in response to Tokyo's slump, but then turned sharply lower with the benchmark South Korean index falling 3 percent. Australian shares dropped 2.6 percent and Hong Kong about 4 percent.

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MARKET TURMOIL SPREADS TO OIL AND METALS

Commodity prices also slumped on reports of mounting radiation levels in parts of Japan as investors scrambled out of riskier assets.

Brent crude for April fell $1.87 to $111.80 a barrel at 10:56 p.m. ET after trading as low as $111.49. U.S. crude for April dropped $1.88 to $99.31.

Even gold, a traditional safe-haven investment, was hit.

Spot gold lost $2.50 an ounce to $1,424.15 an ounce by 8:34 p.m. ET, after rising as much as 1 percent on Monday.

Three-month copper on the London Metal Exchange reversed early gains to edge down 0.4 percent at $9,160 a metric tons by 10:59 p.m. ET.

People are going for risk aversion, so investors are liquidating assets and positions including in crude oil and gold, said Tetsu Emori, a fund manager at Tokyo-based Astmax Co Ltd.

BANK OF JAPAN SEEKS TO EASE PAIN

Euroyen futures edged higher and short-dated swap contracts dipped on Tuesday following the Bank of Japan's offered to pump 5 trillion yen ($61 billion) into the banking system after injecting a record 15 trillion yen in same-day market operations on Monday and eased monetary policy further by expanding its asset buying program.

Ten-year Japanese government bond futures rose half a point to 140.42, on the way to testing the high for the year, helped by safety bids and following a rout in the stock market.

The U.S. Federal Reserve's policy-making Federal Open Markets Committee meets on Tuesday and although the Fed is seen exiting its stimulus earlier than Japan, few are expecting policy to change during this meeting.

U.S. Treasuries rallied on the global flight to safe assets as risk aversion overpowered concerns Japanese insurers would sell Treasuries to fund payouts at home.

Yields on 10-year U.S. Treasuries fell further to 3.22 percent from 3.37 percent earlier in the day.

(Additional reporting by Chikafumi Hodo and Antoni Slodkowski in Tokyo, Vikram S Subhedar in Hong Kong, Clare Jim in Taipei, Cecile Lefort in Sydney; Editing by Richard Borsuk.)

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