Lawyer Ma Dongxiao, representing Shenzhen-based Proview Technology in a trademark dispute with Apple Inc, is surrounded by journalists outside a court in Shanghai on Wednesday. [Photo/China Daily]

Han Ziwen, a proud Apple customer, displays his newly purchased iPads outside the US tech firm's flagship store in Beijing on Sept 17, 2010. Like many others, Han had lined up outside the store for 60 hours to be one of the first to buy an iPad in China. However, the product could be pulled from the shelves if Apple loses its trademark dispute with Shenzhen Proview Technology. [Photo/AFP]

Heated exchanges in trademark dispute, report Wu Yiyao in Shanghai and Tang Yue in Beijing.

Attorneys for Shenzhen Proview Technology and Apple went head-to-head on Wednesday during a heated hearing in Shanghai over the bitter iPad trademark dispute.

The first session was adjourned after four hours, during which Proview denied having sold the right to use the iPad trademark to Apple, while the US tech giant rejected calls for a sales ban on its tablet computers.

Lawyers for the plaintiff and defendant were repeatedly admonished by the presiding judge and told to respect court protocol during arguments. No date was set for a verdict or second hearing.

At the heart of the dispute is the sale of the trademark by Proview's Taiwan affiliate to an Apple subsidiary in 2009.

Xie Xianghui, representing the Shenzhen LCD maker, argued that the transfer was invalid, as it was incomplete. In evidence, Proview presented its IPAD - Internet Personal Access Device - to show it was the first to register the trademark and produce a product.

Apple's use of the iPad name has also made it hard for the Chinese company to sell the trademark, such as to Chinese phone makers and PC maker, Xie said, adding that this means Proview may be unable to repay its bank debts.

However, Hu Jinnan, Apple's attorney, countered that Proview has not marketed or sold its IPAD for years, thus potentially invalidating its claim to the trademark.

The US tech firm also presented copies of e-mails as evidence that Proview was aware of the trademark sale and that the parent company was involved during the process.

A sales ban of the iPad in China will affect a large group, including consumers, added Hu.

Xie dismissed the argument and added that a block on the use of the trademark was unlikely to hurt Apple's profit margins.

Just 50 people were admitted into the gallery to watch the proceedings, which have attracted worldwide attention and thrown a spotlight on trademark disputes in China.

Shu Jianxin, an intellectual property attorney in Shanghai who has been following the case closely, said that if Proview is successful, Apple's tablet computers could be pulled from shelves within 48 hours.