His talk with Xinhua via mobile phone was interrupted by house keeping. " I feel like I was taking a business trip. The only difference is that I cannot go out," he said.

As of midnight on Monday, none of the passengers aboard AM098 have shown flu-like symptoms, according to China's Health Ministry.

Cheng Jun, deputy head of the Ditan hospital, said Beijing's health workers had already taken samples from the 15 passengers for rapid test of the A/H1N1 virus.

Results from the CDC showed that they were negative for A/H1N1 flu virus. But Cheng said the results of rapid tests were not totally reliable as there were possibilities of false negative or false positive results.

"Therefore, seven-day quarantine is a must," he said.

Zeng said he believed quarantine was necessary and all passengers were cooperative.

"I think it's better to avoid contacting others. It's better to be cautious now. This is in the interests of everyone," he said.

However, not everyone was "cooperative" with the quarantine.

Mexican Foreign Minister Patricia Espinosa Cantellano said Saturday that China's quarantine of some Mexican citizens with no symptoms of the virus was discriminatory and short of scientific evidence.

The Mexican Foreign Ministry had reminded Mexican citizens not to travel to China until it corrected the discriminatory measures.

A Mexican Embassy official said that there were nearly 70 Mexicans quarantined across China, mainly in Beijing, Shanghai and Guangzhou.

China rejected the charge, calling for Mexico to be "objective and calm."

"The measures are not targeted at Mexican citizens, and are not discriminatory. This is purely a question of health inspection and quarantine," Foreign Ministry spokesman Ma Zhaoxu said Monday.

Dr Hans Troedsson, WHO Representative in China, told Xinhua Tuesday that the WHO does not have details on the circumstances under which Mexican citizens have been quarantined in China.

But he said in general WHO recommends all countries to limit the spread of and mitigate the impact of the Influenza A (H1N1) virus in the community.

"One measure is quarantine. Other measures include social distancing, as well as advising the public to take simple personal precautions such as avoiding people who appear unwell and washing their hands frequently," he said.

"How each country implements quarantine measures depends on thecontext and must be in accordance with public health regulations and national laws," he said.

"Overall, WHO is very pleased with how China has handled the situation with influenza A (H1N1)," Troedsson said, when asked whether China has been over-the-top in its prevention of A/H1N1 flu.

The spat over quarantine will probably be settled after China and Mexico agreed to send chartered flights to each other's countries to fetch their citizens on Monday.

A Mexican chartered plane has arrived at the Shanghai Pudong International Airport on Tuesday. The plane picked up 43 crew and passengers on board the AM098 and 34 others, who worked and lived in China but were not under quarantine.

The plane then will fly to Beijing to pick up eight Mexicans quarantined in Zeng's hotel. The other two chose to stay in Beijing. The plane will also fly to Guangzhou and Hong Kong to pick up more Mexicans before leaving for Mexico.

Also on Tuesday, a total of 79 Chinese citizens left Mexico City aboard a chartered flight sent by the Chinese government. The Boeing 770-200 is expected to return to Shanghai on Wednesday, according to its operator, Guangzhou-based China Southern Airlines.

Zeng said he has been following the news of the chartered planes. One of his colleagues is still in Mexico and he hoped the colleague could take the chartered plane back home.

Zeng and his colleague, who arrived in Mexico City on April 9, originally were assigned to work in Mexico for one year. But the A/H1N1 flu broke the plan.

"I hope the flu outbreak could come to an end soon so that lifecould return to normal," said he.

(Xinhua News Agency May 6, 2009)