Shipments of the highly anticipated Apple Watch are reportedly being slowed by a faulty component manufactured by one of Apple's suppliers in China.

The Wall Street Journal said the problem centers on a part called the taptic engine, a component designed to mimic being tapped on the wrist. The engine powers a small rod back and forth to alert users in lieu of a vibration or a ringer.

Apple discovered that some taptic engines supplied by AAC Technologies Holdings Inc. in the southern factory hub of Shenzhen began to falter, according to the Journal report.

Watches with the broken parts were being scrapped and Apple is hoping to increase production at the company's second supplier, Nidec Corp. of Japan. Apple is also looking at adding new suppliers such as Hon Hai Precision Industry Co., better known as Foxconn, the report said.

Apple told the Los Angeles Times it won't comment on "rumor and speculation."

The setback complicates the rollout of the Apple Watch, which is only being offered online and in a handful of special boutiques. It is not available in Apple retail stores, the result of limited supplies and the need to market the watch differently from other Apple products.

"Apple Watch is also our most personal product yet, with multiple case and band options because it's an object of self-expression," wrote Angela Ahrendts, Apple's head of retail, in a memo to employees. "Given the high interest and initial supply at launch, we will be able to get customers the model they want earlier and faster by taking orders online."

Analysts expect Apple to sell between eight and 10 million watches in the first year.