The Swiss franc firmed against the dollar early on Tuesday as concerns of further terrorist attacks after last Thursday's train bombs in Madrid stoked demand for safe-have assets such as the Swiss currency.
The US unit eased to 1.2729/39 francs from 1.2795/99 late on Monday in Europe. The euro idled at 1.5639/45 francs from 1.5641/46.
The franc typically strengthens in times of geopolitical security tensions as investors become more risk-averse, switching their assets into safe-havens. But any moves tend to affect dollar/franc more than euro/franc.
Dealers said that if the franc, seen as the world's prime safe haven currency, began to rise quickly on the euro, the Swiss National Bank might take action to slow the currency, but the SNB was not overly concerned about a weaker dollar.
A fall of the euro below 1.50 francs might kick the SNB into action, dealers said.