"A temporary growth slowdown in Japan will have a modest short-term impact on the region," it said.

Though the bank did not offer its own forecast about the likely cost of Japan's disaster, it cited private estimates that the losses could range from $122 billion to $235 billion, or 2.5 to 4 percent of the country's GDP. The 1995 Kobe earthquake caused $100 billion in damage, or about 2 percent of GDP.

Private insurers are likely to bear a small proportion of the cost, leaving most to be covered by households and the government, the World Bank said.

Swiss Re estimates that claims costs in Japan will total $1.2 billion, net of retrocession (the purchase of reinsurance by a reinsurance company) and before tax.

However, the estimates are subject to a high degree of uncertainty as events continue to unfold, making loss assessment particularly challenging, said Swiss Re in a statement on Monday.