Japanese shares were hammered amid reports that highly toxic plutonium was leaking from the Fukushima Dai-ichi power plant, crippled by a huge earthquake and tsunami on March 11. Plant operator Tokyo Electric Power Co. said it was the first confirmed presence of the dangerously radioactive substance and that it was leaking onto the soil outside.

Tokyo's Nikkei 225 index plummeted 1.5 percent in early trading to 9,338.98.

"Radiation fears at Japan's nuclear plant have increased after high levels were detected at the No. 2 reactor — this will continue to be watched closely and is already weighing on Japanese equities today," Bank of America Merrill Lynch said in a report.

Shares in Hitachi Ltd. and Toshiba Corp., which build nuclear power plants, fell 2.5 percent and 2.8 percent respectively. Shares in Japanese companies expecting to play a major role in rebuilding the country's quake-shattered northeast also drooped as preoccupation with the nuclear crisis mounted.

Construction company Kajima Corp. plummeted 2.5 percent; and Komatsu Ltd., a maker of construction equipment, was down 2.2 percent.

Elsewhere, Hong Kong's Hang Seng index lost 0.2 percent to 23,027.67. Benchmarks in mainland China and Singapore were also lower. South Korea's Kospi index slipped marginally to 2,055.21.

Shares in Taiwan and New Zealand were higher, as was Australia's S&P ASX 200 — by 0.1 percent to 4,739.50, despite some heavy losses among mining shares. Energy Resources of Australia Ltd., a uranium miner, plunged 3.5 percent.

In New York on Monday, stocks closed with slight losses after falling in the last half-hour of trading. Major indexes had been up for most of the day after several economic reports suggested that the recovery is continuing amid rising consumer spending and pending home sales.

The Dow Jones industrial average fell 0.2 percent to 12,197.88. The broader S&P 500 index lost 0.3 percent, to 1,310.19. The Nasdaq composite fell 0.5 percent to 2,730.68. Each index had been up more than 0.4 percent earlier in the day.

Oil prices fell to near $103 a barrel in Asia as traders eyed gains by Libyan rebels seeking to topple Moammar Gadhafi and restart dormant crude exports from the OPEC nation.

The euro was lower at $1.4075 from $1.4097 on Monday in New York. The dollar was unchanged at 81.70 yen.

This is a data-heavy week on Wall Street. A crucial jobs report and manufacturing surveys will be released over the next five days.