Tokyo's Nikkei stock index fell 5.95 percent in the afternoon, to its lowest level since November, following Friday's earthquake and tsunami that have so far left almost 1,600 people dead and swept away towns on the northeast coast. Fears were heightened on Monday as scientists worked to try to prevent a meltdown in a quake-hit nuclear plant, with a further explosion at one of its reactors. Among car makers Toyota and Nissan plunged more than 10 percent at one point before recovering slightly. Toyota was 7.23 percent off in the afternoon while Nissan was 8.52 percent down and Honda dropped 3.77 percent. Shares in plant operator Tokyo Electric Power (TEPCO) and Tohoku Electric Power remained ask-only on concerns about the nuclear power plant shutdowns. Toshiba fell by its 16 percent daily limit to 411. Sony was off 9.01 percent at 2,553. The catastrophe in Japan hit markets around the region, with Hong Kong down 0.51 percent by the break, Sydney off 0.71 percent and Seoul 0.94 percent down. Shanghai edged down 0.04 percent. As the Nikkei sank to lows not seen since November the Bank of Japan injected 15 trillion yen ($184 billion) into the short-term money market to support confidence. The fund provision is the largest ever by the Bank of Japan.

"We will take every possible measure, including providing liquidity, to ensure the stability of financial markets and smooth settlements (of business deals)," a bank spokesman said. The move sent the yen racing to its highest level versus the greenback since November, hitting 80.60 to the dollar before easing back. In early afternoon Tokyo trade the dollar changed hands at 82.08 yen against 81.91 in New York late Friday. The euro traded at 114.31 yen, compared with 113.89 in New York. Prime Minister Naoto Kan said in a televised national address Sunday that the country was facing its worst crisis since the end of World War II.

"The current situation of the earthquake, tsunami and the nuclear plants is in a way the most severe crisis in the 65 years since World War II," he said.

Oil slipped on concerns demand from Japan will drop off. New York's main contract, light sweet crude for delivery in April, dipped $1.28 to $99.88 per barrel and Brent North Sea crude for April delivery lost $1.39 to $112.45. However, Chen Xin Yi, commodities analyst for Barclays Capital said prices were likely to pick up later as fuel oil imports rise due to the lost nuclear power capacity.

Gold opened at $1,422.00-$1,423.00 an ounce in Hong Kong, up from Friday's close of $1,415.00-$1,416.00.