Xi Jinping has reaffirmed his commitment to China’s controversial zero-Covid strategy, warning against “any slackening” in the effort and vowing to crack down on criticism of the policy despite signs of damage to the economy.

The comments were published by state media after a meeting on Thursday of the Communist party’s politburo standing committee, the country’s most influential political body that is chaired by the president.

“Our prevention and control policies can withstand the test of history, our measures are scientific and effective. We have won the battle to defend Wuhan, we can also win the battle to defend Shanghai,” the statement said.

China’s leaders also signaled deeper concern with the vulnerabilities of the country’s healthcare system, noting a “great deal of uncertainty concerning how the pandemic will develop”.

“Relaxation will undoubtedly lead to massive numbers of infections, critical cases and deaths, seriously impacting economic and social development and people’s lives and health,” the statement said.

The direction set by China’s top political body bucks rising domestic and international criticism amid a series of lockdowns that have confined tens of millions of people to their homes across the country in an effort to stop the spread of the Omicron variant.

Ting Lu, Nomura’s chief China economist, noted that the politburo “did not mention” reconciling China’s focus on eliminating the virus with economic growth or minimising the damage to the economy, unlike previous meetings.

Xi’s high-profile endorsement of zero-Covid compounded the drag on markets, with global investors dumping stocks on concerns over the impact of future rate rises by the US Federal Reserve.

Chinese tech stocks that are heavily exposed to domestic consumer activity were among the hardest hit, with Alibaba tumbling more than 7 percent and Tencent falling more than 5 percent.

China’s CSI 300 index of Shanghai- and Shenzhen-listed stocks shed as much as 2.5 percent, while in Hong Kong the benchmark Hang Seng index was down as much as 5-5 percent.