Public health officials are warning the Swiss maker of the drug Tamiflu to boost its own production or share its patent with other manufacturers so enough could be made for use in a potential bird flu pandemic. The plea came at an international bird flu conference in Ottawa that brings together health ministers from 30 countries.

The big Swiss pharmaceutical company Roche is coming under increasing pressure to share its formula for Tamiflu. Because there is no bird flu vaccine, Tamiflu is considered the best available medicine as fears mount that the virus will mutate into a form that can spread easily among humans.

The westward spread of the disease from its roots in East Asia is causing Tamiflu orders from governments to soar, but Roche is limited in its ability to fill them.

News reports quote Indian authorities as saying they would consider invoking a special law allowing its drug makers to copy Tamiflu if the company does not license others to produce it.

Canadian health minister Ujjal Dosanjh, the host of the two-day avian flu conference, says a country that is battling bird flu could not be blamed if it broke Roche's patent and produced its own version of the medicine.

"We have regulations in our country to allow us in an emergency to deal with that kind of issue and we will," Mr. Dosanjh says. "Of course, the initial process is talking to Roche and trying to negotiate with them, but if we needed in an emergency our own production and we could produce those substances, we will be looking at that very, very quickly. No country is going to allow, if it can help, for people to die."

Mr. Dosanjh spoke after a statement from Roche warning countries against producing Tamiflu without its permission.

The company has agreed to begin talks with four U.S. drug makers about granting them a license to produce the medicine. It acted last week after two U.S. senators expressed their unhappiness with Roche's limited ability to meet growing world demand.

But Roche says the manufacturing process is complicated and potentially dangerous chemically to workers if companies make the compound without its help.

World Health Organization Director General Lee Jong-Wook told reporters at the Ottawa bird flu conference that developing a generic version without the company's advice could take many months or a few years. He points out that, for this reason, Roche's cooperation is very important in the effort to prevent a bird flu pandemic.

"I hope that they can share the license so that they can share some information so that the others who are willing to make it can make it in a shorter time in an easier way," Mr. Lee says. "It's not only if we can break the patent we can produce all this medicine in big quantities. It's not the case. In reality, there's a practical problem."

But Mr. Lee also warns against relying too heavily on Tamiflu without taking other measures to fight a possible bird flu pandemic. He says widespread use of the drug will eventually allow the virus to develop resistance to it.

A major strategy being discussed at the Ottawa conference is to increase cooperation between the public health and veterinary sectors in countries where humans have close contact with birds so the virus can be stopped at its source before infecting people.

The head of the World Organization for Animal Health, Alejandro Thiermann, says early detection is fundamental to this goal. One tactic he describes is to encourage poultry farmers to report stricken fowl by promising them compensation for the animals they would have to kill.

"The more effort we put at the beginning of the chain, the less likely it is that we're going to have use the tools that we are working on to prevent a pandemic and to treat one if it happens," Mr. Thiermann says.