Because of concern about a possible bird-flu pandemic and a shortage of medicines, Roche Holding AG said it is giving government purchases of its antiviral drug, Tamiflu, precedence over private purchases.

As the pharmaceutical company builds up production facilities, it said it will be able to fill current government orders for Tamiflu, which is considered the best available treatment, by 2007.

Roche for the first time disclosed its production capacity at a briefing yesterday at its headquarters in Basel, Switzerland. Roche said it is able to produce 55 million treatment courses of Tamiflu a year and plans to increase that to 150 million next year and to 300 million by 2007.

Roche cannot be sure there will be sustained, long-term demand for so much Tamiflu, said William M. Burns, chief executive of Roche's pharmaceuticals division. "Our expectation is that governments will continue to enhance the response they can give," he said. "We are trying to keep ahead of the curve."

Burns tried to discourage the public from making panicked purchases of Tamiflu. To combat such buying, Roche temporarily stopped supplying Tamiflu to drug wholesalers in the United States, though Burns said Roche would start shipping the drug again when signs of the regular flu season appear. Tamiflu was designed to treat regular seasonal flu, which kills hundreds of thousands of people worldwide a year.

To help increase production, Roche last month said it was willing to consider allowing outside parties to make or help make Tamiflu. Roche has received more than 150 requests from third parties and has begun talks with eight such parties, including generic and branded pharmaceutical companies and the governments of Taiwan and Vietnam.

Roche said Tuesday that it is considering allowing Vietnam to carry out the final step of Tamiflu production -- putting bulk Tamiflu powder into capsules. The method would save Vietnam money.

The biggest drugmaker in China, Shanghai Pharmaceutical (Group) Co., said yesterday that it has started researching how to produce a generic version of Tamiflu.

Separately, U.S. biotechnology company Amgen Inc. sued Roche, accusing it of infringing six patents covering Amgen's Epogen anemia treatment.

Roche said it is confident its Cera anemia drug, which awaits U.S. regulatory approval, does not infringe Amgen's U.S. patents, adding that Cera is covered by its own patent.

Mei Fong and Zhou Yang contributed to this article.