BEIJING, May 14, 2009 (AFP) - Six years after its sluggish response to SARS, China has been criticised for overreacting to swine flu, showing it still has to find the right prescription for dealing with a health crisis, experts say.

With memories of the Severe Acute Respiratory Disease crisis still fresh, China reacted quickly and aggressively to swine flu to keep the A(H1N1) virus outbreak from its shores.

But although China has learned from its attempted cover-up of the more deadly SARS in 2003, it has miscalculated the severity of the swine flu threat, upsetting other countries as a result, say the experts.

"The Chinese leaders do not understand the need to avoid overreaction. Their understanding of the foreign media and foreign public opinion has always been astonishingly inadequate," said Cheng Li, a China scholar at the Brookings Institution, a Washington think-tank.

China has aggressively screened incoming foreigners, suspending flights to and from Mexico - where the virus first emerged - and quarantining many foreigners.

Mexico complained bitterly at the Chinese moves, saying China was discriminating against its citizens by quarantining them even when they had no flu symptoms and had not travelled from Mexico. Canadian officials have raised similar concerns.

Such measures were imposed despite warnings from the World Health Organisation (WHO) that they would have "very little effect" in containing the virus.

China and its southern territory of Hong Kong have so far confirmed four cases, all of them involving travellers from abroad.

"China's swift and decisive action indicated the government had learned from the SARS episode that cover-up or inaction was not only impossible, but counterproductive," said Yanzhong Huang, director of the Center for Global Health Studies at Seton Hall University in the United States.

"What the government is now doing, however, also suggests that it failed to differentiate between the viruses in terms of virulence and transmissibility."

Beijing also banned pork imports from Mexico and areas of the United States and Canada where A(H1N1) has appeared - prompting Canada to threaten a World Trade Organisation complaint - even though eating pork poses no risk.

"The measures taken by (China) are causing problems in its relations with other countries and the already bruised economy - pork prices dropped significantly because of the fear of pork products," Huang said.

The WHO has been supportive of the swift Chinese action, with its China representative Hans Troedsson telling AFP the response has been "adequate" and "transparent."

But he added: "In areas where China has taken additional measures that significantly interfere with international travel and trade, WHO is in contact with the Chinese government to find out the reasons and justifications for their actions."

Chinese officials initially tried to cover up SARS to prevent a politically embarrassing health threat from being exposed, only coming clean after it began to spill into neighbouring countries.

Though preferable to a cover-up, the swine flu response shows that the political need to appear proactive in the wake of SARS may have once again trumped science-based public health considerations, experts said.

"The Chinese leaders' emphasis on the collective well-being of the public is often at the expense of individual basic human rights," the Brookings Institution's Li said.