Apple's trademark application for its smart watch "iWatch" may hit an unexpected stumbling block on the Chinese mainland, as a similar trademark "iWatching" is already registered, Beijing News reported.

Nine companies have registered the trademark for "iWatch" in China, and three of them were classified as watch and computer peripheral equipment, which are in the same category as Apple's iWatch. However, these trademarks are labeled as invalid, according to the website of the Trademark Office of the State Administration for Industry and Commerce.

"So far, the iWatch trademark is available, as the three companies' iWatch trademarks are expired, which means any companies and individuals can apply for the trademark in accordance with legal procedures, including Apple," said Guo Guozhong, a lawyer from Shanghai's Positive Policy Law firm.

However, there is a similar trademark, iWatching, which has not expired, according to the trademark website. That trademark is successfully registered by a Taiwan-based company under the computer peripheral equipment category.

"iWatching is a trademark similar to iWatch. As a result, if Apple seeks the iWatch trademark in the computer peripheral equipment category, they will get into trouble," Guo said.

Apple China has not responded to the issue.

Apple's trademark problems mounted in China in recent years, from iPhone to iPad, and the company has paid huge sums to settle those trademark suits. Chinese Hanwang Technology Co transferred its "i-phone" trademark to Apple for 24.94 million yuan ($4 million) in July 2009.

In 2012, Apple lost the iPad trademark case in China and paid $60 million to Taiwan-based Proview International Holding.

"Apple could get the iWatch trademark in two ways. First, Apple can apply to cancel the trademark holders' right. According to Chinese law, a trademark can be canceled, if it was not used in three years. Apple once tried to use this to settle the iPad trademark dispute with Proview, but it failed, as Proview proved they had used the iPad trademark during the three years," said Yu Guofu, a senior IT lawyer.

"Second, Apple can negotiate with trademark holders to buy the trademark, otherwise Apple has to give up the name iWatch or the lucrative Chinese mainland market," he added.