Moody's cited an expected decline of the Irish government's financial strength and the country's weaker economic growth outlook as reasons for the downgrade.

The franc was up 0.05 percent against the euro compared to the New York close, trading at 1.2924 per euro at 0650 GMT.

The franc was also buoyed by Thursday's news that the Swiss ZEW investor sentiment jumped by 22.3 points in April to 8.8 points, moving into positive territory for the first time since last August.

"The franc was also supported by increased demand for safe haven assets amid European debt concerns," said Credit Suisse economist Marcus Hettinger, but added he expects the franc to ease in the coming month to around 1.32 per euro.

"We remain bullish EUR/CHF due to wide interest rates spreads and positive technical momentum," he said.

The Swiss National Banks has kept rates ultra-low since the crisis but solid economic fundamentals and the recent rate hike by the European Central Bank have made a Swiss move more likely. Markets currently price in a hike for September.

The franc was down against the dollar at 0.8933 per dollar, after nearing on Thursday the record high it hit on March 17 of 0.8852 according to EBS.

"USD/CHF is heading to the 0.8850 recent low. This will ideally hold the initial test for recovery," said Commerzbank technical analyst Karen Jones. "Beyond the correction, we favour recovery to the 55-day moving average at 0.9302."