(Adds statement from Foxconn "gathering facts", Apple CEO'splant visit this year)
SAN FRANCISCO, Oct 5 (Reuters) - Thousands of workers wenton strike Friday at a Foxconn plant in central China that makesApple Inc's iPhone 5, paralyzing production of thesmartphone, the rights advocate group China Labor Watchreported.
The reported strike comes at a crucial time for the U.S.corporation, weeks after kicking off its largest-ever globalrollout of the smartphone. Apple is already struggling withsupply constraints, analysts say.
Citing workers, the labor group said 3,000 to 4,000 workersbegan their strike at Foxconn's Zhengzhou complex in centralChina in the afternoon, angered by over-exacting qualitycontrols as well as demands they work through the week-longNational Day holidays, which began on Monday.
The strike could not be immediately confirmed, and nor wasit clear whether the stoppage was over or continuing. SomeChinese media carried reports of the China Labor Watch account,but did not offer any verification.
Apple declined to comment. A Foxconn spokesman said thecompany was "gathering facts" on the reported strike and wouldissue a statement when ready.
Tensions have boiled over repeatedly in factories operatedby Foxconn, the Taiwanese contract manufacturing giant thatemploys more than a million and makes most of the world's iPadsand iPhones. Last month, thousands rioted at its Taiyuanfacility in northern China, disrupting production for about 24hours and underscoring the potential for labor unrest.
"In addition to demanding that workers work during theholiday, Foxconn raised overly strict demands on product qualitywithout providing worker training for the corresponding skills,"the Watch said in a statement on its website ().
"Additionally, quality control inspectors fell intoconflicts with workers and were beat up multiple times byworkers. Factory management turned a deaf ear to complaintsabout these conflicts and took no corrective measures."
The group did not say in its release when work might resume.
Foxconn Technology Group of Taiwan, the trading name of HonHai Precision Industry Co , is the world's largestcontract maker of electronics for global brands such as HewlettPackard Co , Nokia and Dell Inc .
Apple and Foxconn have come under fire for poor workingconditions and wages at plants across China. In response, theyhave organized an audit of factory conditions, raised wages,improved safety and reduced overtime, among other measures.
Apple's chief executive officer Tim Cook visited Foxconn'svast complex on the far outskirts of Zhengzhou in late March.
(Reporting By Edwin Chan; Additional reporting by JonathanStanding in Taipei; Editing by Richard Chang and SanjeevMiglani)
Keywords: APPLE FOXCONN/