The dollar index slipped to a 4-month low on Thursday, as the investors continue to favor the currencies such as Swiss franc and yen amid escalating nuclear crisis in Japan.

The dollar index, which measures the performance of the greenback against a basket of six other major currencies, fell to 75.995, its lowest level since Nov. 5.

The euro, which accounts for over half of the dollar index’s trade-weightage, rose above $1.4000, nearing the peak of $1.4036 hit in 2011.

However, the investors await debt auction by Spain on Thursday, as the country sells as much as 4.5 billion euros ($6.3 billion) of 30-year debt and 10-year securities.

The Swiss franc surged to a fresh all-time high of 0.8967 against the dollar on Thursday ahead of interest rate decision by the Swiss National Bank (SNB). SNB kept rates unchanged at 0.25 pct as expected.

The Swiss government said that the high debt levels of many countries along with a recent earthquake in Japan would pose risks to the growth of the global economy, Reuters reported.

The Japanese yen surged to an all-time high of 76.39 against the US dollar late Wednesday (New York time). Previously, the all-time high was 79.75, made in 1995.

Japanese vice trade minister Motohisa Ikeda dismissed speculations of yen repatriation behind the currency's surge, saying that there is no sign of yen repatriation by Japanese companies.