Updated

The Mexican capital will begin to return to normal this week after much of the city was closed due to the deadly new flu virus, Mexico City Mayor Marcelo Ebrard said Monday.

Health Secretary Jose Cordova says most economic activity will resume Wednesday, ending a five-day closure of nonessential businesses to stop the spread of the new virus.

Cordova says Mexico has confirmed 727 cases, including 26 deaths.

Mexico City Mayor Marcelo Ebrard says cafes, museums and libraries will reopen this week but that health officials need to finish inspecting schools before students can return to class. Elementary schools in particular will stay closed until May 11, Ebrard said. Students age 15 and older will return to school Thursday, he said.

Bars, restaurants, theaters and cinemas will stay closed until there is stronger evidence that the threat from the H1N1 virus has receded, Cordova said.

Meanwhile, Mexican officials are angry about China's decision to quarantine more than 70 Mexicans over swine flu fears sent a plane Monday to the communist country to bring its citizens back home. China sent its own plane to retrieve Chinese nationals stranded in Mexico.

Mexico is believed to be the source of the swine flu outbreak that has led to more than 1,000 cases in 20 countries throughout the world.

Mexico is upset because Chinese health officials have quarantined more than 70 Mexican travelers even though some are apparently not at risk for the virus.

In one case, a Mexican couple and their three small children were rousted from their hotel room at 4 a.m. and transported to a hospital, said Jorge Guajardo, the Mexican ambassador to Beijing.

None of those in isolation has presented symptoms and most had no contact with infected persons or places, he said.

About a third of the confirmed U.S. cases of swine flu are people who had been to Mexico and likely picked up the infection there, according to the Centers for Disease Control and Prevention.

As of Monday, the CDC said the U.S. had 286 in 36 states.

Meanwhile, the World Health Organization has no plans at this time to raise its pandemic alert level above a 5, U.N. chief Ban Ki-moon said Monday. Phase 5 is just one level below a full-fledged pandemic on the six-phase scale.

There is also still no evidence of community-level spread of the new flu H1N1 virus outside North America, Keiji Fukuda, WHO acting assistant director-general, told reporters.

"We continue to see a number of infections related to travel in a number of different countries ... and a little bit of movement of the virus going south," he said.

"We do not have any evidence that the virus has taken hold and has led to community-level transmissions in any other country right now (outside North America).

"It is not that surveillance has to be strong just in the southern hemisphere. It has to be strong everywhere. Right now we really just don't know how this will go," Fukuda said.

There have been 1,025 laboratory cases, including 26 deaths, and the cases have been seen in 20 countries, he said.

Fukuda said the WHO had concerns about the infection travelling to the southern hemisphere because winter is setting in when flu viruses typically thrive.

He said the spectrum of illness was from very mild cases to cases which end in fatalities.

The Associated Press and Reuters contributed to this report.