MEXICO CITY — Mexico is telling citizens to stay home, urging businesses to close for five days and suspending government services as the World Health Organization warns the swine flu outbreak is on the brink of becoming a global epidemic.

In the United States, where swine flu has been confirmed in 11 states, President Barack Obama told Americans the government was "taking the utmost precautions and preparations" to stop the virus.

Mexican President Felipe Calderon said in a televised address that only essential businesses such as supermarkets, hospitals and pharmacies should stay open, and only critical government workers such as police and soldiers would be on duty from tomorrow through Tuesday. School had already been canceled nationwide through Tuesday.

The steps are aimed at stopping further spread of the virus, blamed for 168 deaths in Mexico and one in the United States, even though the WHO has suggested nations should focus on minimizing its effects, not containing its spread.

"There will be no government activities — those that are not fundamental for citizens — nor any private-sector activities that are not fundamental to common life," Calderon said last night in a televised address.

"There is no safer place to protect yourself against catching swine flu than in your house," he said, defending the government against criticism that it had been slow to act against signs of a new and dangerous virus.

In the U.S., both Vice President Joe Biden and the acting head of the Centers for Disease Control and Prevention said in televised interviews today there would be no practical benefit to closing the U.S.-Mexican border. Biden said on CBS that it would be a "monumental undertaking" with far-reaching consequences.

Biden also said on NBC's "Today" show that he is advising his own family to stay off commercial airlines and even subways because of swine flu. If one person sneezes on a confined aircraft, he said, "it goes all the way through the aircraft."

Within two hours, Biden's office issued a statement backing off the remarks and suggesting he was talking about travel to Mexico.

His precautions go beyond official advice from the U.S. government; Obama merely urged people to wash their hands, cover their coughs and stay home when they feel sick. Calderon gave similar advice.

The WHO yesterday raised its alert level to Phase 5, the second-highest, indicating a pandemic may be imminent, and was talking about moving to Phase 6. The Phase 5 alert — the first ever — activates added efforts to produce a vaccine.

"It really is all of humanity that is under threat during a pandemic," WHO Director General Margaret Chan said in Geneva. "We do not have all the answers right now, but we will get them."

Switzerland and the Netherlands became the latest countries to report swine flu infections. In addition to Mexico and the U.S., Canada, New Zealand, Britain, Germany, Spain, Israel and Austria have confirmed cases.

The Swiss government said a 19-year-old student with swine flu was mistakenly released from the hospital and then hastily readmitted. The Dutch said a 3-year-old child who recently returned from Mexico had contracted swine flu and was being treated and recovering well.

European Union health ministers planned emergency talks in Luxembourg to coordinate national efforts in preventing the spread of swine flu in Europe.

WHO flu chief Dr. Keiji Fukuda said it was difficult to say whether the outbreak justified declaring a Phase 6 pandemic.

By definition, he said, a pandemic means "established transmission of this new virus in multiple countries and multiple regions of the world. So right now we're saying that we see it convincingly in two countries in one region of the world."

"We think we are in the process of moving toward there, but we still need to see the evidence that we are there," Fukuda said.