UPDATE 2-Brazil CS cane crush up 25 pct but rains slow pace

* Rains slow harvesting, reduce sugar content

* 6 new mills became operational in June/July

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SAO PAULO, July 15 (Reuters) - Brazil's 2009/10 center-south cane crush was up 25 percent by June 30 from a year ago but rains slowed the pace of crushing last month, the Sugar Cane Industry Association (Unica) said on Wednesday.

Since April 1 through the end of June, mills in the region crushed 176.2 million tonnes of cane, up from 141.2 million tonnes in the same period a year ago.

But the amount of cane crushed in the second half of June totaled only 33.2 million tonnes, down 0.7 percent from the 33.5 million tonnes crushed in the same period a year ago as showers forced several mills to stop harvesting for days.

"The occurrence of rains during June in some areas ... reduced the time available for crushing and the amount of sugar in the harvested cane," Unica said in its latest crop report.

"The reduction wasn't bigger thanks to 10 mills that came online during the fortnight, three out of them new plants."

Four new mills came on stream in June and another two facilities became operational in the first half of July. Of all mills in the center-south, 20 have not started crushing the 2009/10 cane crop yet, Unica said.