TOKYO - Asian shares fell sharply Tuesday, battered by ongoing unrest in the Middle East, an earthquake in New Zealand and a downgrade of Japan's credit rating outlook.

Oil prices, meanwhile, soared to near $93 a barrel Tuesday in Asia as Libyan leader Moammar Gadhafi struggled to keep power of the OPEC nation amid violent protests.

The Nikkei 225 stock average shed almost 2 percent to 10,646.22, Hong Kong's Hang Seng index lost 1.7 percent to 23,084.92, and South Korea's Kospi was down 2.1 percent at 1,964.07.

Japan's ability to tackle its massive debt came under scrutiny after Moody's Investors Service downgraded its outlook for Japan's credit rating. The rating agency on Tuesday changed its outlook for Japan's Aa2 rating from stable to negative.

The move comes less than a month after Standard & Poor's cut Japan's sovereign debt rating.

Stock markets in Taiwan, Singapore and the Chinese mainland also retreated. New Zealand's benchmark lost 0.9 percent to 3,351.14 after a powerful earthquake hit the city of Christchurch. The temblor collapsed buildings and buried vehicles under debris as police tried to confirm reports of multiple deaths.

Meanwhile, sentiment was hurt by fears that the political unrest in Libya is worsening, which is pushing oil prices sharply higher. US markets were closed Monday for a national holiday.

In currency markets, the dollar rose slightly to 83.16 yen. The euro was down at $1.3608 from $1.3645.