Tian Lipu, Commissioner of China's State Intellectual Property Office, said the Beijing Municipal First Intermediate People's Court has accepted Pfizer Pharmaceutical's petition.

"The case is still in judicial procedures," Tian said, "We are confident that Chinese judicial authorities will handle the case in line with laws,"

Tian made the remarks during an on-line interview held by the central government's website in reply to a netizen's question on the issue. The patent for Pfizer's Viagra was revoked in China in July, 2004. Pfizer launched its suit two months after its patent was revoked.

Viagra is a pill used to treat erectile dysfunction and has become one the most popularly prescribed drugs in the world.

"In accordance with China's relevant laws the party that has its patent revoked can bring the case to the People's court for administrative litigation," said Tian.

"Both the granting and revoking of Viagra's patent complied with legitimate procedures," Tian added.

Tian said he hoped that the parties concerned claim their rights in line with China's laws.

Viagra, developed by the Pfizer Pharmaceuticals, is one of the most counterfeited drugs in the world. China cracked such a case in Shaoxing of east China's Zhejiang Province last month involving 280,000 fake Viagra pills with price value more than 238 million yuan (about 30 million U.S. dollars).

E.D. drugs such as Viagra and Cialis were approved by the Ministry of Health and State Food and Drug Administration as prescription drugs in 1999.