* Index at 59.6 points in Dec vs 61 in Reuters poll
* Manufacturing still growing strongly but franc hurting
* Safe-haven franc hitting new records
ZURICH, Jan 3 (Reuters) - Activity in Switzerland's manufacturing sector slowed slightly more than expected in December, although still growing at a robust pace, as the strong Swiss franc weighed on the export-dominated economy.
The Swiss purchasing managers' index fell to a seasonally adjusted 59.6 points in December from 61.8 points in the previous month and compared with a median forecast in a Reuters poll for 61 points, data showed on Monday.
The index is compiled by the Swiss SVME purchasing managers' association and Credit Suisse, which noted the index had been hovering around 60 points since August, well above the growth threshold of 50 points but below highs of early 2010.
"With the exception of output, all of the subcomponents that feed into the calculation of the PMI lost ground compared with the previous month," they said. "Those subcomponents which point more towards future trends slipped back within the growth zone."
Last week, a smaller-than-expected dip in the leading KOF economic barometer in December indicated the brisk recovery of the Swiss economy looks set to slow only slightly in the first half of 2011 despite the soaring Swiss franc.
"The Swiss purchasing managers' index fell unexpectedly in December. The Swiss economy, however, is still poised for growth," said VP Bank economist Joerg Zeuner.
"The only sore point is the strong Swiss franc which is climbing from record high to record high versus the euro and the dollar. If this development continues, the export and tourism industries will come to feel it more during the course of the year and this will impact total economic growth negatively."
The Swiss National Bank, which expects the economy to grow by some 1.5 percent in 2011, said after it kept rates on hold last month the soaring Swiss franc was set to hit exports and lead to a "significant" overall slowdown.
The safe-haven franc has hit new record highs against the euro and the dollar in recent days and business leaders such as the head of watchmaker Swatch Group have voiced concern over the currency's strength. (Reporting by Emma Thomasson; Editing by Ruth Pitchford)