The Italian election "is not causing widespread panic yet, " said Sean Callow, senior currency strategist at Westpac Institutional Bank in Sydney.

WSJ: Asian Shares Down; Nikkei Underperforms

"It is one of those strange moves because we can't attribute it to a payrolls report or Japanese economic news, " said Sean Callow, senior currency strategist at Westpac in Sydney.

WSJ: Nikkei Jumps As Dollar Surges Through ?100

"Every decline in the yen against the US dollar means Japan is paying for more for its energy needs - it's a steep rise in costs for everybody, " said Sean Callow, senior currency strategist at Westpac.

BBC: Yen breaches 100 threshold mark against US dollar